I found this Cheat Sheet and thought I would link to it as it could be very useful.

WPF XAML Data Binding Cheat Sheet

I was putting code in my ViewModel that returns Visibility but I didn’t really like that very much. If the UI is created with something other than WPF, that is really not going to work. Since I intend to do cross compile my code in Mono, which doesn’t have WPF but uses either Forms or GTK#, I have already encountered this issue. What I really want to use is bool.

The solution is IValueConverter. If you just want the code and don’t want to read this post, just scroll to the bottom and grab the

IValueConverter is part of PresentationFramework (in PresentationFramework.dll) so it isn’t available in Mono, but that is OK because you don’t instantiate it in the ViewModel, you use it in the View so it will only be used when the GUI is part of WPF. So if you are separating your View into a separate DLL, this would be included in the View DLL, that way when you compile everything else, with say a different GUI that uses GTK#, you won’t get a compiler error because PresentationFramework doesn’t exist in Mono.

BooleanToVisibilityConverter

Well, there is an object already created for you called BooleanToVisibilityConverter, but it is limited. True is converted Visibility.Visible. False is converted to Visibility.Collapsed.

Here we see a problem. Visibility has three possible values but a Boolean only has two.

This will cover many of the scenarios, but not all.

Here is how it would be used.

For this example, I have this Person class.

    public class Person
    {
        public Person() { }
        public String FirstName { get; set; }
        public String LastName { get; set; }
        public String Age { get; set; }
    }

Here is a simple View for this object. It has a Grid that has a Label and TextBox for each property in the Person object. It also has a CheckBox. The CheckBox gives us a easy bool value, IsChecked. This works similar to a bool property in a ViewModel.

<Window x:Class="TestBooleanToVisibilityConverter.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:TestBooleanToVisibilityConverter"
        Title="MainWindow"
        SizeToContent="WidthAndHeight"
        >
    <Grid Margin="20">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <Grid Name="PersonViewGrid">
            <Grid.Resources>
                <BooleanToVisibilityConverter x:Key="BoolToVisConverter"/>
            </Grid.Resources>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto" />
                <ColumnDefinition Width="Auto" />
            </Grid.ColumnDefinitions>
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto" />
                <RowDefinition Height="Auto" />
                <RowDefinition Height="Auto" />
            </Grid.RowDefinitions>
            <Label Content="First Name:" Grid.Column="0" Grid.Row="0" />
            <TextBox Grid.Column="1" Grid.Row="0" Name="firstNameTextBox"
                     Text="{Binding Path=FirstName, Mode=TwoWay, ValidatesOnExceptions=true, NotifyOnValidationError=true}" MinWidth="175" />
            <Label Content="Last Name:" Grid.Column="0" Grid.Row="1" />
            <TextBox Grid.Column="1" Grid.Row="1" Name="lastNameTextBox"
                     Text="{Binding Path=LastName, Mode=TwoWay, ValidatesOnExceptions=true, NotifyOnValidationError=true}" MinWidth="175" />
            <Label Content="Age:" Grid.Column="0" Grid.Row="2"
                   Visibility="{Binding IsChecked, ElementName=ShowAgeCheckBox, Converter={StaticResource BoolToVisConverter}}"/>
            <TextBox Grid.Column="1" Grid.Row="2" Name="ageTextBox"
                     Text="{Binding Path=Age, Mode=TwoWay, ValidatesOnExceptions=true, NotifyOnValidationError=true}" MinWidth="175"
                   Visibility="{Binding IsChecked, ElementName=ShowAgeCheckBox, Converter={StaticResource BoolToVisConverter}}"/>
        </Grid>
        <Grid Grid.Row="1">
            <CheckBox Name="ShowAgeCheckBox" Content="Show Age" />
        </Grid>
    </Grid>
</Window>

I am not using MVVM for this example, but instead there is a just a single object created in the code behind for demo purposes.

using System;
using System.Windows;

namespace TestBooleanToVisibilityConverter
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent(); Person p = new Person() { FirstName = "Michael", LastName = "Michaels", Age = "33" };
            PersonViewGrid.DataContext = p;
        }

    }
}

Ok, now build the project and you will see that the Label and TextBox for Age are hidden until you check the box.

Writing your own Bool to Visibility Converter

Sometimes you may need to write you own Converter.  For example, in the above project, it is annoying how the CheckBox moves up and down in position because Visibility.Collapsed is used instead of Visibility.Hidden.  You may want to use Visibility.Hidden instead.

You can write your own Converter that returns Visibility.Hidden instead of Visibility.Collapsed.

BooleanToVisibleOrHidden.cs

using System;
using System.Windows.Data;
using System.Windows;

namespace TestBooleanToVisibilityConverter
{
    class BoolToVisibleOrHidden : IValueConverter
    {
        #region Constructors
        /// <summary>
        /// The default constructor
        /// </summary>
        public BoolToVisibleOrHidden() { }
        #endregion

        #region IValueConverter Members
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            bool bValue = (bool)value;
            if (bValue)
                return Visibility.Visible;
            else
                return Visibility.Hidden;
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            Visibility visibility = (Visibility)value;

            if (visibility == Visibility.Visible)
                return true;
            else
                return false;
        }
        #endregion
    }
}

Here we do the conversion ourselves and now we have a different conversion table.

Now replace the Converter object in your XAML.  We only change Line 15.

      <local:BoolToVisibleOrHidden x:Key="BoolToVisConverter"/>

This works, but it could be improved. This still leaves us having to choose between two objects.

Creating a Converter that supports a choice of Hidden or Collapsed.

Here we will provide a property that determines if we should collapse or not.

Add a property called Collapse and return the appropriate Visibility based on that property. Here is the new object. As you see, the code changes to add this feature is really just an empty bool property and an if statement that used the bool property.

using System;
using System.Windows.Data;
using System.Windows;

namespace TestBooleanToVisibilityConverter
{
    class BoolToVisibleOrHidden : IValueConverter
    {
        #region Constructors
        /// <summary>
        /// The default constructor
        /// </summary>
        public BoolToVisibleOrHidden() { }
        #endregion

        #region Properties
        public bool Collapse { get; set; }
        #endregion

        #region IValueConverter Members
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            bool bValue = (bool)value;
            if (bValue)
            {
                return Visibility.Visible;
            }
            else
            {
                if (Collapse)
                    return Visibility.Collapsed;
                else
                    return Visibility.Hidden;
            }
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            Visibility visibility = (Visibility)value;

            if (visibility == Visibility.Visible)
                return true;
            else
                return false;
        }
        #endregion
    }
}

Now in your XAML you have the option to do nothing, which uses the bool default value false, or to set the Collapse property to true as shown below.

      <local:BoolToVisibleOrHidden x:Key="BoolToVisConverter" Collapse="True"/>

We now support either feature with the following table. We probably at this point would rename the object to BooleanToVisibilityConverter, but Microsoft already took that object name so I will leave it named as is.

We are starting to get a little more usability from one object.

Adding the Reverse feature so False is Visible and True is Collapsed or Hidden

Lets say we want to change the CheckBox so that instead of saying “Show Age” it says “Hide Age”.

            <CheckBox Name="ShowAgeCheckBox" Content="Hide Age" />

Now we have to reverse the mapping. If Reverse=”True” we want the mapping to be like this:

This is also quite simple. We add another bool property called Reverse. Then key of that in another if statement.

using System;
using System.Windows.Data;
using System.Windows;

namespace TestBooleanToVisibilityConverter
{
    class BoolToVisibleOrHidden : IValueConverter
    {
        #region Constructors
        /// <summary>
        /// The default constructor
        /// </summary>
        public BoolToVisibleOrHidden() { }
        #endregion

        #region Properties
        public bool Collapse { get; set; }
        public bool Reverse { get; set; }
        #endregion

        #region IValueConverter Members
        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            bool bValue = (bool)value;

                if (bValue != Reverse)
                {
                    return Visibility.Visible;
                }
                else
                {
                    if (Collapse)
                        return Visibility.Collapsed;
                    else
                        return Visibility.Hidden;
                }
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            Visibility visibility = (Visibility)value;

                if (visibility == Visibility.Visible)
                    return !Reverse;
                else
                    return Reverse;
        }
        #endregion
    }
}

Now you can reverse this very easily in the XAML.

      <local:BoolToVisibleOrHidden x:Key="BoolToVisConverter" Collapse="True" Reverse="True" />

And now you have a much more full featured converter.

Additional Thoughts

I have to wonder why the developers didn’t do this originally with the BooleanToVisibilityConverter object. It is so simple. This is a perfect example of where Microsoft would benefit from Open Sourcing some of their code. A dozen people would have contributed this change by now if they had and all Microsoft would have to do is look at the submitted code, approve, and check it in.

I have an xml that has a name space. This gave me to problems I had to resolve.

1. How do I deserialize this xml with that name space value?
2. How do I serialize the object to only have this one name space?

Deserializing an Xml with a Name Space

Below is an Xml file. Notice that the PrimaryNode has a name space that isn’t the default.

<?xml version="1.0" encoding="utf-8"?>
<PrimaryNode xmlns="http://some/random/namespace/example>
  <SecondaryNode>
    <TertiaryNode />
    <TertiaryNode />
  </SecondaryNode>
</PrimaryNode>

I had an object created as follows.

using System;
using System.Xml.Serialization;
using System.Collections.ObjectModel;

namespace XmlNameSpaceTest.Model
{
    [Serializable()]
    public class PrimaryNode
    {
        private ObservableCollection<SecondaryNode> _Children;

        public PrimaryNode() { }

        [XmlElement("SecondaryNode")]
        public ObservableCollection<SecondaryNode> Children
        {
            get
            {
                if (_Children == null)
                    _Children = new ObservableCollection<SecondaryNode>();
                return _Children;
            }
        }
    }
}

I used this static class for the serialization

using System;
using System.IO;
using System.Xml.Serialization;

namespace XmlNameSpaceTest.Model
{
    public class Serializer
    {
        #region Functions
        public static void SerializeToXML<T>(T t, String inFilename)
        {
            XmlSerializer serializer = new XmlSerializer(t.GetType());
            TextWriter textWriter = new StreamWriter(inFilename);
            serializer.Serialize(textWriter, t);
            textWriter.Close();
        }

        public static T DeserializeFromXML<T>(String inFilename)
        {
            XmlSerializer deserializer = new XmlSerializer(typeof(T));
            TextReader textReader = new StreamReader(inFilename);
            T retVal = (T)deserializer.Deserialize(textReader);
            textReader.Close();
            return retVal;
        }
        #endregion
    }
}

But it failed to deserialize because of the name space. It gave me this exception (which I trimmed to only show the important parts as it was very long).

System.InvalidOperationException was unhandled
  Message=There is an error in XML document (2, 2).
  Source=System.Xml
  StackTrace:
       <-- snipped -->
  InnerException: System.InvalidOperationException
       Message=<PrimaryNode xmlns='http://some/random/namespace/example'> was not expected.
       Source=bgwwvhdx
       StackTrace:
            at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderPrimaryNode.Read7_PrimaryNode()

The solution was simple. I had to add the XmlRoot tag above the class.

    [Serializable()]
    [XmlRoot(Namespace="http://some/random/namespace/example")]
    public class PrimaryNode
    {
        ... snipped...
    }

This solved problem 1. The Xml now deserialized just fine.

Serializing an Xml so it only contains a single Name Space

When I serialized the object, there were two default name spaces, but neither were the custom name space that the Xml needed.

<?xml version="1.0" encoding="utf-8"?>
<PrimaryNode xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <SecondaryNode>
    <TertiaryNode />
    <TertiaryNode />
  </SecondaryNode>
</PrimaryNode>

Here is what I had to do.

1. Add a XmlSerializerNamespaces property with only the one name space added.

    [Serializable()]
    [XmlRoot(Namespace="http://some/random/namespace/example")]
    public class PrimaryNode
    {
        ... snipped...

        private XmlSerializerNamespaces _Namespaces;

        public XmlSerializerNamespaces NameSpaces
        {
            get
            {
                if (_Namespaces == null)
                {
                    _Namespaces = new XmlSerializerNamespaces();
                    _Namespaces.Add("", "http://schemas.microsoft.com/wix/2006/wi");
                }
                return _Namespaces;
            }
        }
    }

2. Then I had to change my Serializer class. I needed to overload the Serialize function by adding a version of it that accepts the XmlSerializerNamespaces object as the third parameter.

        public static void SerializeToXML<T>(T t, String inFilename, XmlSerializerNamespaces namespaces)
        {
            XmlSerializer serializer = new XmlSerializer(t.GetType());
            TextWriter textWriter = new StreamWriter(inFilename);
            serializer.Serialize(textWriter, t, namespaces);
            textWriter.Close();
        }

3. Then, you’ve probably realized already, when serializing the object to Xml, we use this new function and pass it the PrimaryNode.NameSpaces as the third parameter.

This solved the second problem.

I hope this post helps you.

Hello. Today I had to get mnemonic to work. Mnemonic is the ability to navigate to a control using a key stroke combination. One of the most common mnemonics is Alt + F. Alt + F usually navigates to the File drop down menu in any Window, and most everyone is familiar with this mnemonic.

In WPF, to get mnemonics, you pretty much just put an underscore in front of a word. For example, for Alt + F, you would enter: _File

Well, in WPF I needed to do the Label, TextBox matching, so that the mnemonics is on a Label but the key strokes navigate the keyboard focus to the TextBox.

Lets say you have a simple form in WPF like this:

The XAML to make these work together using mnemonics is simple. The important property is Target.

<Window x:Class="Mnemonics.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" >
    <Grid FocusManager.FocusedElement="{Binding ElementName=textBoxFirstName}">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto"/>
            <ColumnDefinition Width="Auto"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <Label Target="{Binding ElementName=textBoxFirstName}" HorizontalContentAlignment="Right">
            <AccessText TextWrapping="WrapWithOverflow">First _Name:</AccessText>
        </Label>
        <TextBox Name="textBoxFirstName" Width="200" Height="20" Grid.Column="1"/>
        <Label Target="{Binding ElementName=textBoxLastName}" HorizontalContentAlignment="Right" Grid.Row="1">
            <AccessText TextWrapping="WrapWithOverflow">_Last Name:</AccessText>
        </Label>
        <TextBox Name="textBoxLastName" Width="200" Height="20" Grid.Row="1" Grid.Column="1"/>
    </Grid>
</Window>

Lets discuss the code above briefly.

1. Notice line 5 first.  Here I am setting the FocusManager.FocusedElement to the first text box so that you can immediately type in the first field when arriving at the window.
2. Notice the use of AccessText instead of TextBlock (lines 15, 19).  You don’t have to do it this way.  You could have just set the Content property on the label. You don’t need the AccessText at all unless you want to wrap.  If you want to wrap, you have to do it this way.
3. Notice the use of Target (lines 18,14) and how it is bound to the element that should receive focus when the mnemonic keys are pressed.

Hope this helps you.

I just found http://www.wpftutorial.net.

Just another resource for WPF information.

Hey all,

I created an MVVM project and then saved it as a template.  This way when I create new projects, I can simple choose MVVM Base and save a ton of time.

You can use my template if you want.  You can download it here: MVVM Base.zip

How to add the MVVM Base template to your Visual Studio

If you want this to be available as a new project type in you Visual Studio install, follow these steps.

1. go to this path under My Documents:Visual Studio 2010\My Exported Templates
2. Download this template to that directory. MVVM Base.zip
3. Create a new Visual Studio Project and choose MVVM Base from the list of C# projects.

I created a C# DataMeasurement object a while ago but recently really started to use it. I wrote unit tests for it and fixed comparison and add/substract of nulls and wrote Unit tests for it.

The intent of the object is to be able to use any Data size and do the following:

1. Convert it to any other data size type, 1 GB converts to 1024 MB.
2. Compare it to any other data size type, 1 GB = 1024 MB.
3. Add any other data size type and have it add correctly, 1 GB + 1024 MB = 2GB.

So you can easily compare things like 12343 bytes.

You can create the object in a lot of different ways as I have multiple constructors, and it is easy to add your own constructor.

Here is the object:

using System;
using System.Collections.Generic;
using System.Text;

namespace LANDesk.Install.Common
{
    public class DataMeasurement
    {
        #region Member Variables
        // This is the size in the current type. For example, 1 GB = 1.0. But
        // if you convert the Type to Megabyte, the value should change to 1024.0;
        protected Double _DataSize;
        protected DataType _DataType;
        #endregion

        #region Constructors

        /// <summary>
        /// The default constructor.  This initializes and object with a
        /// DataSize of 0 and a DataType of Byte.
        /// </summary>
        public DataMeasurement()
        {
            _DataSize = 0;
            _DataType = DataType.Byte;
        }

        /// <summary>
        /// This constructor takes a value and assumes the data measurement
        /// type is in bytes.
        /// </summary>
        /// <param name="inValue">The measurement value as a ulong.</param>
        public DataMeasurement(UInt64 inSizeInBytes)
        {
            _DataType = DataType.Byte;
            _DataSize = inSizeInBytes * 8;
        }

        /// <summary>
        /// This constructor takes a value and a data measurement type.
        /// </summary>
        /// <param name="inValue">The measurement value as a ulong.</param>
        /// <param name="inType">The measurement type.</param>
        public DataMeasurement(UInt64 inValue, DataType inType)
        {
            _DataType = inType;
            _DataSize = inValue;
        }

        /// <summary>
        /// This constructor takes a double value and defaults to megabyte.
        /// </summary>
        /// <param name="inValue"></param>
        public DataMeasurement(double inValue)
        {
            _DataType = DataType.Megabyte;
            _DataSize = inValue;
        }

        /// <summary>
        /// This constructor takes a value and a data measurement type.
        /// </summary>
        /// <param name="inValue">The measurement value as a double.</param>
        /// <param name="inType">The measurement type.</param>
        public DataMeasurement(double inValue, DataType inType)
        {
            _DataType = inType;
            _DataSize = inValue;
        }

        /// <summary>
        /// This constructor takes a value and a data measurement type.
        /// </summary>
        /// <param name="inValue">The measurement value as a double.</param>
        /// <param name="inType">The measurement type as a string, "GB", "Gigabyte".</param>
        public DataMeasurement(UInt64 inValue, String inType)
        {
            _DataSize = inValue;
            GetDataTypeFromString(inType);
        }

        /// <summary>
        /// This constructor takes a string representation of a data measurement.
        /// </summary>
        /// <param name="inValueAndType">The measurement value and type in a
        /// single string such as "49 GB" or "49 GBSI" or "49 Gigabyte". There
        /// must be a space as it is used to split the value from the type, so
        ///  "49GB" is invalid because there is no space delimeter.</param>
        public DataMeasurement(String inValueAndType)
        {
            char[] split = { ' ' };
            String[] data = inValueAndType.Split(split);
            _DataSize = Convert.ToUInt64(data[0]);
            GetDataTypeFromString(data[1]);
        }
        #endregion

        #region Properties
        public Double Size
        {
            get { return _DataSize; }
            set { _DataSize = value; }
        }

        public DataType DataSizeType
        {
            get { return _DataType; }
            set { _DataType = value; }
        }

        public ShortName DataSizeTypeShortName
        {
            get { return (ShortName)_DataType; }
            set { _DataType = (DataType)value; }
        }

        public ulong Bit
        {
            get { return (ulong)ConvertToType(DataType.Bit, false); }
            set
            {
                _DataType = DataType.Bit;
                _DataSize = value;
            }
        }

        public Double Byte
        {
            get { return ConvertToType(DataType.Byte, false); }
            set
            {
                _DataType = DataType.Byte;
                _DataSize = value;
            }
        }

        public Double KilobitSI
        {
            get { return ConvertToType(DataType.KilobitSI, false); }
            set
            {
                _DataType = DataType.KilobitSI;
                _DataSize = value;
            }
        }

        public Double Kilobit
        {
            get { return ConvertToType(DataType.Kilobit, false); }
            set
            {
                _DataType = DataType.Kilobit;
                _DataSize = value;
            }
        }
        public Double KilobyteSI
        {
            get { return ConvertToType(DataType.KilobyteSI, false); }
            set
            {
                _DataType = DataType.KilobyteSI;
                _DataSize = value;
            }
        }

        public Double Kilobyte
        {
            get { return ConvertToType(DataType.Kilobyte, false); }
            set
            {
                _DataType = DataType.Kilobit;
                _DataSize = value;
            }
        }

        public Double MegabitSI
        {
            get { return ConvertToType(DataType.MegabitSI, false); }
            set
            {
                _DataType = DataType.MegabitSI;
                _DataSize = value;
            }
        }

        public Double Megabit
        {
            get { return ConvertToType(DataType.Megabit, false); }
            set
            {
                _DataType = DataType.Megabit;
                _DataSize = value;
            }
        }
        public Double MegabyteSI
        {
            get { return ConvertToType(DataType.MegabyteSI, false); }
            set
            {
                _DataType = DataType.MegabyteSI;
                _DataSize = value;
            }
        }

        public Double Megabyte
        {
            get { return ConvertToType(DataType.Megabyte, false); }
            set
            {
                _DataType = DataType.Megabyte;
                _DataSize = value;
            }
        }

        public Double GigabitSI
        {
            get { return ConvertToType(DataType.GigabitSI, false); }
            set
            {
                _DataType = DataType.GigabitSI;
                _DataSize = value;
            }
        }

        public Double Gigabit
        {
            get { return ConvertToType(DataType.Gigabit, false); }
            set
            {
                _DataType = DataType.Gigabit;
                _DataSize = value;
            }
        }
        public Double GigabyteSI
        {
            get { return ConvertToType(DataType.GigabyteSI, false); }
            set
            {
                _DataType = DataType.GigabyteSI;
                _DataSize = value;
            }
        }

        public Double Gigabyte
        {
            get { return ConvertToType(DataType.Gigabyte, false); }
            set
            {
                _DataType = DataType.Gigabyte;
                _DataSize = value;
            }
        }

        public Double TerabitSI
        {
            get { return ConvertToType(DataType.TerabitSI, false); }
            set
            {
                _DataType = DataType.TerabitSI;
                _DataSize = value;
            }
        }

        public Double Terabit
        {
            get { return ConvertToType(DataType.Terabit, false); }
            set
            {
                _DataType = DataType.Terabit;
                _DataSize = value;
            }
        }
        public Double TerabyteSI
        {
            get { return ConvertToType(DataType.TerabyteSI, false); }
            set
            {
                _DataType = DataType.TerabyteSI;
                _DataSize = value;
            }
        }

        public Double Terabyte
        {
            get { return ConvertToType(DataType.Terabyte, false); }
            set
            {
                _DataType = DataType.Terabyte;
                _DataSize = value;
            }
        }

        public Double PetabitSI
        {
            get { return ConvertToType(DataType.PetabitSI, false); }
            set
            {
                _DataType = DataType.PetabitSI;
                _DataSize = value;
            }
        }

        public Double Petabit
        {
            get { return ConvertToType(DataType.Petabit, false); }
            set
            {
                _DataType = DataType.Petabit;
                _DataSize = value;
            }
        }
        public Double PetabyteSI
        {
            get { return ConvertToType(DataType.PetabyteSI, false); }
            set
            {
                _DataType = DataType.PetabyteSI;
                _DataSize = value;
            }
        }

        public Double Petabyte
        {
            get { return ConvertToType(DataType.Petabyte, false); }
            set
            {
                _DataType = DataType.Petabyte;
                _DataSize = value;
            }
        }

        public Double ExabitSI
        {
            get { return ConvertToType(DataType.ExabitSI, false); }
            set
            {
                _DataType = DataType.ExabitSI;
                _DataSize = value;
            }
        }

        public Double Exabit
        {
            get { return ConvertToType(DataType.Exabit, false); }
            set
            {
                _DataType = DataType.Exabit;
                _DataSize = value;
            }
        }

        public Double ExabyteSI
        {
            get { return ConvertToType(DataType.ExabyteSI, false); }
            set
            {
                _DataType = DataType.ExabyteSI;
                _DataSize = value;
            }
        }

        public Double Exabyte
        {
            get { return ConvertToType(DataType.Exabyte, false); }
            set
            {
                _DataType = DataType.Exabyte;
                _DataSize = value;
            }
        }
        #endregion

        #region Functions
        /// <summary>
        /// Writes the DataMeasurement to string, such as "1 GB" or "1024 KB".
        /// It always uses the DataSize and DataType values.
        /// </summary>
        override public string ToString()
        {
            return String.Format("{0} {1}", _DataSize, ((ShortName)_DataType).ToString());
        }

        /// <summary>
        /// Writes the DataMeasurement to string, such as "1 GB" or "1024 KB".
        /// However, it does so in the DataType that you specify.
        /// </summary>
        /// <param name="inDataType">The type to output to string. For example
        /// If the measurement is "4 Gigabyte" but you pass in Megabyte, it
        /// will output "4096 MB".</param>
        /// <returns></returns>
        public string ToString(DataType inDataType)
        {
            Double size = ConvertToType(inDataType, false);
            return String.Format("{0} {1}", size, ((ShortName)inDataType).ToString());
        }

        public override int GetHashCode()
        {
            return base.GetHashCode();
        }

        public override bool Equals(object obj)
        {
            if (obj == null)
                return false;

            DataMeasurement right = obj as DataMeasurement;
            if ((object)right == null)
                return false;

            return this == right;
        }

        private void GetDataTypeFromString(String inType)
        {
            if (inType.Length == 2 || inType.Length == 4)
            {   // Short name was used so get the ShortName and case it to a DataType
                // KB and Kb are not the same, so case is Important
                _DataType = (DataType)Enum.Parse(typeof(ShortName), inType, false);
            }
            else
            {   // Long name was used so get
                // We can ignore case because Kilobit and Kilobyte are different.
                _DataType = (DataType)Enum.Parse(typeof(DataType), inType, true);
            }
        }

        /// <summary>
        /// This function converts the stored measurement from its current
        /// value to a new value using the new DataType.
        /// </summary>
        /// <param name="inNewType">The new DataType. For example If the
        /// measurement is "4 Gigabyte" but you pass in Megabyte, it will
        /// change the value to "4096 Megabyte".</param>
        /// <returns>The new DataSize for the new type is returned.</returns>
        public Double ConvertToType(DataType inNewType)
        {
            return ConvertToType(inNewType, true);
        }

        /// <summary>
        /// This function converts the stored measurement from its current
        /// value to a new value using the new DataType.
        /// </summary>
        /// <param name="inNewType">The new DataType.. For example If the
        /// measurement is "4 Gigabyte" but you pass in Megabyte, it will
        /// change the value to "4096 Megabyte".</param>
        /// <param name="inChangeObjectMeasurementType">A bool value that
        /// specifies whether to change the whole object.</param>
        /// <returns>The new DataSize for the new type is returned.</returns>
        public Double ConvertToType(DataType inNewType, bool inChangeObjectMeasurementType)
        {
            double ret = 0;
            bool isSet = false;
            if (inNewType == _DataType)
            {
                ret = _DataSize;
                isSet = true;
            }
            else if (inNewType == DataType.Bit)
            {
                ret = (ulong)_DataType * _DataSize * 8;
                isSet = true;
            }
            else if (_DataType == DataType.Bit)
            {
                ret = _DataSize / 8 / (ulong)inNewType;
                isSet = true;
            }

            if (!isSet)
                ret = (ulong)_DataType * _DataSize / (ulong)inNewType;

            if (inChangeObjectMeasurementType)
            {
                _DataType = inNewType;
                Size = ret;
            }

            return ret;
        }
        #endregion

        #region Operator Override Functions
        public static bool operator ==(DataMeasurement left, DataMeasurement right)
        {
            if (null == (object)left && null == (object)right)
                return true;
            if (null == (object)right || null == (object)left)
                return false;

            if (left.DataSizeType == right.DataSizeType)
            {
                return left.Size == right.Size;
            }
            else
            {
                return left.Byte == right.Byte;
            }
        }

        public static bool operator !=(DataMeasurement left, DataMeasurement right)
        {
            if (null == (object)left && null == (object)right)
                return false;
            if (null == (object)right || null == (object)left)
                return true;

            if (left.DataSizeType == right.DataSizeType)
            {
                return left.Size != right.Size;
            }
            else
            {
                return left.Byte != right.Byte;
            }
        }

        public static bool operator >(DataMeasurement left, DataMeasurement right)
        {
            if (null == (object)left && null == (object)right)
                return false;
            if (null == (object)right)
                return true;
            if (null == (object)left)
                return false;

            if (left.DataSizeType == right.DataSizeType)
            {
                return left.Size > right.Size;
            }
            else
            {
                return left.Byte > right.Byte;
            }
        }

        public static bool operator >=(DataMeasurement left, DataMeasurement right)
        {
            if (left.DataSizeType == right.DataSizeType)
            {
                return left.Size >= right.Size;
            }
            else
            {
                return left.Byte >= right.Byte;
            }
        }

        public static bool operator <(DataMeasurement left, DataMeasurement right)
        {
            if (null == (object)left && null == (object)right)
                return false;
            if (null == (object)right)
                return false;
            if (null == (object)left)
                return true;
            if (left.DataSizeType == right.DataSizeType)
            {
                return left.Size < right.Size;
            }
            else
            {
                return left.Byte < right.Byte;
            }
        }

        public static bool operator <=(DataMeasurement left, DataMeasurement right)
        {
            if (left.DataSizeType == right.DataSizeType)
            {
                return left.Size <= right.Size;
            }
            else
            {
                return left.Byte <= right.Byte;
            }
        }

        public static DataMeasurement operator +(DataMeasurement left, DataMeasurement right)
        {
            return left + right.ConvertToType(left.DataSizeType, false);
        }

        public static DataMeasurement operator +(DataMeasurement left, double right)
        {
            if ((null == (object)left && null == (object)right) || null == (object)right)
                return left;
            if (null == (object)left)
                return new DataMeasurement(right);
            return new DataMeasurement(left.Size + right, left.DataSizeType);
        }

        public static DataMeasurement operator -(DataMeasurement left, DataMeasurement right)
        {
            return left - right.ConvertToType(left.DataSizeType, false);
        }

        public static DataMeasurement operator -(DataMeasurement left, double right)
        {
            if ((null == (object)left && null == (object)right) || null == (object)right)
                return left;
            if (null == (object)left)
                return new DataMeasurement(right);
            return new DataMeasurement(left.Size - right, left.DataSizeType);
        }
        #endregion

        #region Enums
        public enum ShortName : ulong
        {
            b = 0, // Bit must be handled special
            // Everything after is in bytes
            B = 1,
            KbSI = 125,
            Kb = 128,
            KBSI = 1000,
            KB = 1024,
            MbSI = 125000,
            Mb = 131072,
            MBSI = 1000000,
            MB = 1048576,
            GbSI = 125000000,
            Gb = 134217728,
            GBSI = 1000000000,
            GB = 1073741824,
            TbSI = 125000000000,
            Tb = 137438953472,
            TBSI = 1000000000000,
            TB = 1099511627776,
            PbSI = 125000000000000,
            Pb = 140737488355328,
            PBSI = 1000000000000000,
            PB = 1125899906842624,
            EbSI = 125000000000000000,
            Eb = 144115188075855872,
            EBSI = 1000000000000000000,
            EB = 1152921504606846976
        }

        public enum DataType : ulong
        {
            Bit = 0, // Bit must be handled special
            // Everything after is in bytes
            Byte = 1,
            KilobitSI = 125,
            Kilobit = 128,
            KilobyteSI = 1000,
            Kilobyte = 1024,
            MegabitSI = 125000,
            Megabit = 131072,
            MegabyteSI = 1000000,
            Megabyte = 1048576,
            GigabitSI = 125000000,
            Gigabit = 134217728,
            GigabyteSI = 1000000000,
            Gigabyte = 1073741824,
            TerabitSI = 125000000000,
            Terabit = 137438953472,
            TerabyteSI = 1000000000000,
            Terabyte = 1099511627776,
            PetabitSI = 125000000000000,
            Petabit = 140737488355328,
            PetabyteSI = 1000000000000000,
            Petabyte = 1125899906842624,
            ExabitSI = 125000000000000000,
            Exabit = 144115188075855872,
            ExabyteSI = 1000000000000000000,
            Exabyte = 1152921504606846976
        }
        #endregion
    }
}

I could probably do a better job of testing this. Here is a test class that succeeds. If you want more testing add it.

Hopefully this helps you out.

using LANDesk.Install.Common;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Collections.Generic;

namespace LANDesk.Install.Common.Tests
{
    /// <summary>
    ///This is a test class for DataMeasurementTest and is intended
    ///to contain all DataMeasurementTest Unit Tests
    ///</summary>
    [TestClass()]
    public class DataMeasurementTest
    {
        List<DataMeasurement> sizes = new List<DataMeasurement>();

        [TestMethod()]
        public void DataMeasurementTestAdditionAndGreaterThanLessThan()
        {
            DataMeasurementEqualityTest();
            DataMeasurement OneGB = new DataMeasurement("1 GB");
            DataMeasurement OneGBinMB = new DataMeasurement("1024 MB");
            DataMeasurement twoGB = new DataMeasurement(2, DataMeasurement.DataType.Gigabyte);
            DataMeasurement twoGBadded = OneGB + OneGBinMB;
            TestEqualValues(twoGB, twoGBadded);

            foreach (DataMeasurement dm in sizes)
            {
                TestLeftIsGreater(twoGB, dm);
                TestRightIsGreater(dm, twoGB);
            }
        }

        [TestMethod()]
        public void DataMeasurementTestSubtractionAndGreaterThanLessThan()
        {
            DataMeasurementEqualityTest();
            DataMeasurement tenGB = new DataMeasurement(10, DataMeasurement.DataType.Gigabyte);
            DataMeasurement NineGB = new DataMeasurement(9, DataMeasurement.DataType.Gigabyte);
            DataMeasurement NineGBbySubtraction = tenGB - sizes[0];
            TestEqualValues(NineGB, NineGBbySubtraction);
            TestLeftIsGreater(tenGB, NineGB);
            TestLeftIsGreater(tenGB, NineGBbySubtraction);
            TestRightIsGreater(NineGB, tenGB);
            TestRightIsGreater(NineGBbySubtraction, tenGB);
        }

        [TestMethod()]
        public void TestConversion()
        {
            DataMeasurement dm = new DataMeasurement("4 GB");
            dm.ConvertToType(DataMeasurement.DataType.Megabyte);
            Assert.IsTrue(dm.Size == (double)4096);
            Assert.IsTrue(dm.ToString() == "4096 MB");
        }

        [TestMethod()]
        public void DataMeasurementOtherTest()
        {
            sizes = new List<DataMeasurement>();
            int i = -1;

            // Test 1 - Check that conversion is working
            i++;
            sizes.Add(new DataMeasurement("1024 bit"));
            Assert.IsTrue(sizes[i].Bit == 1024, "Test 1, to Bit.");
            Assert.IsTrue(sizes[i].Byte == 1024 / 8, "Test 1, to Byte.");
            double expected = 1024 / 8 / 1024.0;
            Assert.IsTrue(sizes[i].Kilobyte == expected, "Test 1, " + sizes[i].Kilobyte + " should equal " + expected);

            // Test 2 - Check that conversion is working
            i++;
            sizes.Add(new DataMeasurement(4, DataMeasurement.DataType.Gigabyte));
            Assert.IsTrue(sizes[i].Bit == 34359738368, "Test 2, to bit.");
            Assert.IsTrue(sizes[i].Byte == 4294967296, "Test 2, to Byte.");
            Assert.IsTrue(sizes[i].Kilobyte == 4 * 1024 * 1024, "Test 2, to Kilobyte.");
            expected = 4.0 / 1024;
            Assert.IsTrue(sizes[i].Terabyte == expected, "Test 2, " + sizes[i].Terabyte + " should equal " + expected);

            // Test 3 - Comparisons
            Assert.IsTrue(sizes[i - 1] < sizes[i], "Test 3, " + sizes[i - 1] + " is less than " + sizes[i]);
            Assert.IsTrue(sizes[i - 1] <= sizes[i], "Test 3, " + sizes[i - 1] + " is less than or equal to " + sizes[i]);
            Assert.IsFalse(sizes[i - 1] > sizes[i], "Test 3, " + sizes[i - 1] + " is greater than " + sizes[i]);
            Assert.IsFalse(sizes[i - 1] >= sizes[i], "Test 3, " + sizes[i - 1] + " is greater than or equal to " + sizes[i]);
            Assert.IsFalse(sizes[i - 1] == sizes[i], "Test 3, " + sizes[i - 1] + " is equal to " + sizes[i]);
            Assert.IsTrue(sizes[i - 1] != sizes[i], "Test 3, " + sizes[i - 1] + " is not equal to " + sizes[i]);
        }

        public void DataMeasurementEqualityTest()
        {
            DataMeasurement last = null;
            DataMeasurement OneGB = new DataMeasurement("1 GB");
            foreach (DataMeasurement.DataType dt in Enum.GetValues(typeof(DataMeasurement.DataType)))
            {
                DataMeasurement next = new DataMeasurement(OneGB.ConvertToType(dt, false), dt);
                sizes.Add(next);
                if (last != null)
                    TestEqualValues(next, last);
                last = next;
            }
        }

        private void TestEqualValues(DataMeasurement left, DataMeasurement right)
        {
            Assert.IsFalse(left > right);
            Assert.IsFalse(left < right);
            Assert.IsTrue(left >= right);
            Assert.IsTrue(left <= right);
            Assert.IsTrue(left == right);
            Assert.IsFalse(left != right);
            Assert.IsTrue(left.Equals(right));
        }

        private void TestLeftIsGreater(DataMeasurement left, DataMeasurement right)
        {
            Assert.IsTrue(left > right);
            Assert.IsFalse(left < right);
            Assert.IsTrue(left >= right);
            Assert.IsFalse(left <= right);
            Assert.IsFalse(left == right);
            Assert.IsTrue(left != right);
        }

        private void TestRightIsGreater(DataMeasurement left, DataMeasurement right)
        {
            Assert.IsFalse(left > right);
            Assert.IsTrue(left < right);
            Assert.IsFalse(left >= right);
            Assert.IsTrue(left <= right);
            Assert.IsFalse(left == right);
            Assert.IsTrue(left != right);
        }
    }
}

I hope this object helps save you time.

Example 1 – .NET 4 Example

using Microsoft.Win32;

namespace Read64bitRegistryFrom32bitApp
{
    class Program
    {
        static void Main(string[] args)
        {
            string value64 = string.Empty;
            string value32 = string.Empty;

            RegistryKey localKey = RegistryKey.OpenBaseKey(Microsoft.Win32.RegistryHive.LocalMachine, RegistryView.Registry64);
            localKey = localKey.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion");
            if (localKey != null)
            {
                value64 = localKey.GetValue("RegisteredOrganization").ToString();
            }
            RegistryKey localKey32 = RegistryKey.OpenBaseKey(Microsoft.Win32.RegistryHive.LocalMachine, RegistryView.Registry32);
            localKey32 = localKey32.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion");
            if (localKey32 != null)
            {
                value32 = localKey32.GetValue("RegisteredOrganization").ToString();
            }
        }
    }
}

.NET 3.5 SP1 and Prior

Example 1 – A console application to read the 64 bit registry from a 32 bit application or vice versa

using System;
using System.Runtime.InteropServices;
using System.Text;

namespace Read64bitRegistryFrom32bitApp
{
    class Program
    {
        static void Main(string[] args)
        {
            string value64 = GetRegKey64(RegHive.HKEY_LOCAL_MACHINE, @"SOFTWARE\Microsoft\Windows NT\CurrentVersion", "RegisteredOrganization");
            Console.WriteLine(value64);
            string value32 = GetRegKey32(RegHive.HKEY_LOCAL_MACHINE, @"SOFTWARE\Microsoft\Windows NT\CurrentVersion", "RegisteredOrganization");
            Console.WriteLine(value32);
        }

        public enum RegSAM
        {
            QueryValue = 0x0001,
            SetValue = 0x0002,
            CreateSubKey = 0x0004,
            EnumerateSubKeys = 0x0008,
            Notify = 0x0010,
            CreateLink = 0x0020,
            WOW64_32Key = 0x0200,
            WOW64_64Key = 0x0100,
            WOW64_Res = 0x0300,
            Read = 0x00020019,
            Write = 0x00020006,
            Execute = 0x00020019,
            AllAccess = 0x000f003f
        }

        public static UIntPtr HKEY_LOCAL_MACHINE = new UIntPtr(0x80000002u);
        public static UIntPtr HKEY_CURRENT_USER = new UIntPtr(0x80000001u);

        #region Member Variables
        #region Read 64bit Reg from 32bit app
        [DllImport("Advapi32.dll")]
        static extern uint RegOpenKeyEx(
            UIntPtr hKey,
            string lpSubKey,
            uint ulOptions,
            int samDesired,
            out int phkResult);

        [DllImport("Advapi32.dll")]
        static extern uint RegCloseKey(int hKey);

        [DllImport("advapi32.dll", EntryPoint = "RegQueryValueEx")]
        public static extern int RegQueryValueEx(
            int hKey, string lpValueName,
            int lpReserved,
            ref uint lpType,
            System.Text.StringBuilder lpData,
            ref uint lpcbData);
        #endregion
        #endregion

        #region Functions
        static public string GetRegKey64(UIntPtr inHive, String inKeyName, String inPropertyName)
        {
            return GetRegKey64(inHive, inKeyName, RegSAM.WOW64_64Key, inPropertyName);
        }

        static public string GetRegKey32(UIntPtr inHive, String inKeyName, String inPropertyName)
        {
            return GetRegKey64(inHive, inKeyName, RegSAM.WOW64_32Key, inPropertyName);
        }

        static public string GetRegKey64(UIntPtr inHive, String inKeyName, RegSAM in32or64key, String inPropertyName)
        {
            //UIntPtr HKEY_LOCAL_MACHINE = (UIntPtr)0x80000002;
            int hkey = 0;

            try
            {
                uint lResult = RegOpenKeyEx(RegHive.HKEY_LOCAL_MACHINE, inKeyName, 0, (int)RegSAM.QueryValue | (int)in32or64key, out hkey);
                if (0 != lResult) return null;
                uint lpType = 0;
                uint lpcbData = 1024;
                StringBuilder AgeBuffer = new StringBuilder(1024);
                RegQueryValueEx(hkey, inPropertyName, 0, ref lpType, AgeBuffer, ref lpcbData);
                string Age = AgeBuffer.ToString();
                return Age;
            }
            finally
            {
                if (0 != hkey) RegCloseKey(hkey);
            }
        }
        #endregion
    }
}

Example 2 – A static class to read the 64 bit registry from a 32 bit application or vice versa

using System;
using System.Runtime.InteropServices;
using System.Text;

namespace Read64bitRegistryFrom32bitApp
{
    public enum RegSAM
    {
        QueryValue = 0x0001,
        SetValue = 0x0002,
        CreateSubKey = 0x0004,
        EnumerateSubKeys = 0x0008,
        Notify = 0x0010,
        CreateLink = 0x0020,
        WOW64_32Key = 0x0200,
        WOW64_64Key = 0x0100,
        WOW64_Res = 0x0300,
        Read = 0x00020019,
        Write = 0x00020006,
        Execute = 0x00020019,
        AllAccess = 0x000f003f
    }

    public static class RegHive
    {
        public static UIntPtr HKEY_LOCAL_MACHINE = new UIntPtr(0x80000002u);
        public static UIntPtr HKEY_CURRENT_USER = new UIntPtr(0x80000001u);
    }

    public static class RegistryWOW6432
    {
        #region Member Variables
        #region Read 64bit Reg from 32bit app
        [DllImport("Advapi32.dll")]
        static extern uint RegOpenKeyEx(
            UIntPtr hKey,
            string lpSubKey,
            uint ulOptions,
            int samDesired,
            out int phkResult);

        [DllImport("Advapi32.dll")]
        static extern uint RegCloseKey(int hKey);

        [DllImport("advapi32.dll", EntryPoint = "RegQueryValueEx")]
        public static extern int RegQueryValueEx(
            int hKey, string lpValueName,
            int lpReserved,
            ref uint lpType,
            System.Text.StringBuilder lpData,
            ref uint lpcbData);
        #endregion
        #endregion

        #region Functions
        static public string GetRegKey64(UIntPtr inHive, String inKeyName, String inPropertyName)
        {
            return GetRegKey64(inHive, inKeyName, RegSAM.WOW64_64Key, inPropertyName);
        }

        static public string GetRegKey32(UIntPtr inHive, String inKeyName, String inPropertyName)
        {
            return GetRegKey64(inHive, inKeyName, RegSAM.WOW64_32Key, inPropertyName);
        }

        static public string GetRegKey64(UIntPtr inHive, String inKeyName, RegSAM in32or64key, String inPropertyName)
        {
            //UIntPtr HKEY_LOCAL_MACHINE = (UIntPtr)0x80000002;
            int hkey = 0;

            try
            {
                uint lResult = RegOpenKeyEx(RegHive.HKEY_LOCAL_MACHINE, inKeyName, 0, (int)RegSAM.QueryValue | (int)in32or64key, out hkey);
                if (0 != lResult) return null;
                uint lpType = 0;
                uint lpcbData = 1024;
                StringBuilder AgeBuffer = new StringBuilder(1024);
                RegQueryValueEx(hkey, inPropertyName, 0, ref lpType, AgeBuffer, ref lpcbData);
                string Age = AgeBuffer.ToString();
                return Age;
            }
            finally
            {
                if (0 != hkey) RegCloseKey(hkey);
            }
        }
        #endregion

        #region Enums
        #endregion
    }
}

using System;
using System.Runtime.InteropServices;
using System.Text;

namespace Read64bitRegistryFrom32bitApp
{
    class Program
    {
        static void Main(string[] args)
        {
            string value64 = RegistryWOW6432.GetRegKey64(RegHive.HKEY_LOCAL_MACHINE, @"SOFTWARE\Microsoft\Windows NT\CurrentVersion", "RegisteredOrganization");
            string value32 = RegistryWOW6432.GetRegKey32(RegHive.HKEY_LOCAL_MACHINE, @"SOFTWARE\Microsoft\Windows NT\CurrentVersion", "RegisteredOrganization");
        }
    }
}

Example 3 – Adding extension methods to the managed RegistryKey object that read the 64 bit registry from a 32 bit application or vice versa

using System;
using System.Runtime.InteropServices;
using System.Text;
using Microsoft.Win32;

namespace Read64bitRegistryFrom32bitApp
{
    /// <summary>
    /// An extension class to allow a registry key to allow it to get the
    /// registry in the 32 bit (Wow6432Node) or 64 bit regular registry key
    /// </summary>
    public static class RegistryWOW6432
    {
        #region Member Variables
        #region Read 64bit Reg from 32bit app
        public static UIntPtr HKEY_LOCAL_MACHINE = new UIntPtr(0x80000002u);
        public static UIntPtr HKEY_CURRENT_USER = new UIntPtr(0x80000001u);

        [DllImport("Advapi32.dll")]
        static extern uint RegOpenKeyEx(
            UIntPtr hKey,
            string lpSubKey,
            uint ulOptions,
            int samDesired,
            out int phkResult);

        [DllImport("Advapi32.dll")]
        static extern uint RegCloseKey(int hKey);

        [DllImport("advapi32.dll", EntryPoint = "RegQueryValueEx")]
        public static extern int RegQueryValueEx(
            int hKey, string lpValueName,
            int lpReserved,
            ref uint lpType,
            System.Text.StringBuilder lpData,
            ref uint lpcbData);
        #endregion
        #endregion

        #region Functions
        public static string GetRegKey64(this RegistryKey inKey, String inPropertyName)
        {
            string strKey = inKey.ToString();
            string regHive = strKey.Split('\\')[0];
            string regPath = strKey.Substring(strKey.IndexOf('\\') +1);
            return GetRegKey64(GetRegHiveFromString(regHive), regPath, RegSAM.WOW64_64Key, inPropertyName);
        }

        public static string GetRegKey32(this RegistryKey inKey, String inPropertyName)
        {
            string strKey = inKey.ToString();
            string regHive = strKey.Split('\\')[0];
            string regPath = strKey.Substring(strKey.IndexOf('\\') + 1);
            return GetRegKey64(GetRegHiveFromString(regHive), regPath, RegSAM.WOW64_32Key, inPropertyName);
        }

        private static UIntPtr GetRegHiveFromString(string inString)
        {
            if (inString == "HKEY_LOCAL_MACHINE")
                return HKEY_LOCAL_MACHINE;
            if (inString == "HKEY_CURRENT_USER")
                return HKEY_CURRENT_USER;
            return UIntPtr.Zero;
        }

        static public string GetRegKey64(UIntPtr inHive, String inKeyName, RegSAM in32or64key, String inPropertyName)
        {
            //UIntPtr HKEY_LOCAL_MACHINE = (UIntPtr)0x80000002;
            int hkey = 0;

            try
            {
                uint lResult = RegOpenKeyEx(inHive, inKeyName, 0, (int)RegSAM.QueryValue | (int)in32or64key, out hkey);
                if (0 != lResult) return null;
                uint lpType = 0;
                uint lpcbData = 1024;
                StringBuilder AgeBuffer = new StringBuilder(1024);
                RegQueryValueEx(hkey, inPropertyName, 0, ref lpType, AgeBuffer, ref lpcbData);
                string Age = AgeBuffer.ToString();
                return Age;
            }
            finally
            {
                if (0 != hkey) RegCloseKey(hkey);
            }
        }
        #endregion

        #region Enums
        public enum RegSAM
        {
            QueryValue = 0x0001,
            SetValue = 0x0002,
            CreateSubKey = 0x0004,
            EnumerateSubKeys = 0x0008,
            Notify = 0x0010,
            CreateLink = 0x0020,
            WOW64_32Key = 0x0200,
            WOW64_64Key = 0x0100,
            WOW64_Res = 0x0300,
            Read = 0x00020019,
            Write = 0x00020006,
            Execute = 0x00020019,
            AllAccess = 0x000f003f
        }
        #endregion
    }
}

using System;
using System.Runtime.InteropServices;
using System.Text;
using Microsoft.Win32;

namespace Read64bitRegistryFrom32bitApp
{
    class Program
    {
        static void Main(string[] args)
        {
            string value64 = string.Empty;
            string value32 = string.Empty;
            RegistryKey localKey = Registry.LocalMachine;
            localKey = localKey.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion");
            if (localKey != null)
            {
                value32 = localKey.GetRegKey32("RegisteredOrganization");
                value64 = localKey.GetRegKey64("RegisteredOrganization");
            }
        }
    }
}

• RegOpenKeyEx Function – http://msdn.microsoft.com/en-us/library/ms724897%28v=VS.85%29.aspx
• RegQueryValueEx Function – http://msdn.microsoft.com/en-us/library/ms724911%28VS.85%29.aspx
• http://www.pinvoke.net/default.aspx/advapi32/RegQueryValueEx.html
• http://www.pinvoke.net/default.aspx/advapi32/RegOpenKeyEx.html
• http://www.pinvoke.net/default.aspx/advapi32/RegCreateKeyEx.html
• http://www.pinvoke.net/default.aspx/advapi32/RegCloseKey.html
• http://stackoverflow.com/questions/1470770/accessing-registry-using-net
• http://connect.microsoft.com/VisualStudio/feedback/details/400597/registeredorganization-reg-key-on-x64-vista-7

Copyright ® Rhyous.com – Linking to this post is allowed without permission and as many as ten lines of this page can be used along with this link. Any other use of this page is allowed only by permission of Rhyous.com.

I needed to generate a random password in C# and I wanted to do it right.

I consulted a security expert and he mentioned that I should use a seed created with RNGCryptoServiceProvider so I did a search and quickly found this blog entry that had a good start.
http://eyeung003.blogspot.com/2010/09/c-random-password-generator.html

However, I needed three enhancements to this code.

1. Store the password as a SecureString.
2. Make upper case and lower case characters separate options.
3. Guarantee that each character option would be used.

So I added these enhancements. Here are some notes about the enhancements:

• SecureString – Since most password code requires strings instead of secure strings, even code such as a SQL connection strings, I cannot fault the original writer for leaving the password as a string. However, passwords should be stored as SecureString objects as much as possible. With my enhancements, it still flips back and forth between secure string and string, but hopefully is a SecureString as often as possible.
• I include the ability to convert the SecureString to a string, because of the issue mentions in the previous bullet point.
• I separated the character options. I also added back the characters that were listed as confusing. If someone thinks these are confusing, use a font where they are not confusing or remove them again.
• Using all options – I guarantee that each option is used. The first characters in the password are chosen, one from each option, in a random order. I still didn’t like that, I created a scramble but in order to create the scramble, I had pull the password out as a string to get each character to scramble.
• I also added some exception objects to make exceptions clear if there are any.
• I also tested this on C# (Mono) on FreeBSD and it works.

Ok, here is the new version that includes my enhancements to the original code.

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Cryptography;

namespace System.Security
{
    public enum CharacterTypes : byte
    {
        Alpha_Lower = 1,
        Alpha_Upper = 2,
        Alpha_Upper_and_Lower = 3,
        Digit = 4,
        AlphaLowerNumeric = Digit + Alpha_Lower,        //  5 (4+1)
        AlphaUpperNumeric = Digit + Alpha_Upper,        //  6 (4+2)
        AlphaNumeric = Alpha_Upper_and_Lower + Digit,   //  7 (4+3)
        Special = 8,
        // You could add more character types here such as Alpha_Lower  + Special, but why?
        AlphaNumericSpecial = AlphaNumeric + Special    // 15 (8+7)
    }

    public class RandomPasswordGenerator
    {
        // Define default password length.
        private static int DEFAULT_PASSWORD_LENGTH = 16;

        private static PasswordOption AlphaLC = new PasswordOption() { Characters = "abcdefghijklmnopqrstuvwxyz", Count = 0 };
        private static PasswordOption AlphaUC = new PasswordOption() { Characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ", Count = 0 };
        private static PasswordOption Digits = new PasswordOption() { Characters = "0123456789", Count = 0 };
        private static PasswordOption Specials = new PasswordOption() { Characters = "!@#$%^&*()~<>?", Count = 0 };

        #region Overloads

        /// <summary>
        /// Generates a random password with the default length.
        /// </summary>
        /// <returns>Randomly generated password.</returns>
        public static SecureString Generate()
        {
            return Generate(DEFAULT_PASSWORD_LENGTH,
                            CharacterTypes.AlphaNumericSpecial);
        }

        /// <summary>
        /// Generates a random password with the default length.
        /// </summary>
        /// <returns>Randomly generated password.</returns>
        public static SecureString Generate(CharacterTypes option)
        {
            return Generate(DEFAULT_PASSWORD_LENGTH, option);
        }

        /// <summary>
        /// Generates a random password with the specified length.
        /// </summary>
        /// <returns>Randomly generated password.</returns>
        public static SecureString Generate(int passwordLength)
        {
            return Generate(passwordLength,
                            CharacterTypes.AlphaNumericSpecial);
        }

        /// <summary>
        /// Generates a random password.
        /// </summary>
        /// <returns>Randomly generated password.</returns>
        public static SecureString Generate(int passwordLength,
                                      CharacterTypes option)
        {
            return GeneratePassword(passwordLength, option);
        }

        #endregion

        /// <summary>
        /// Generates the password.
        /// </summary>
        /// <returns></returns>
        private static SecureString GeneratePassword(int passwordLength, CharacterTypes option)
        {
            // Password length must at lest be 1 character long
            if (passwordLength < 1)
                throw new InvalidPasswordLengthException();

            // Character type must be a valid CharacterType
            if (option < CharacterTypes.Alpha_Lower || option > CharacterTypes.AlphaNumericSpecial)
                throw new InvalidPasswordCharacterTypeException();

            PasswordOptions passwordOptions = GetCharacters(option);

            // Make sure the password is long enough.
            // For example CharacterTypes.AlphaNumericSpecial
            // requires at least 4 characters: 1 upper, 1 lower, 1 digit, 1 special
            if (passwordLength < passwordOptions.Count)
                throw new InvalidPasswordLengthException();

            SecureString securePassword = new SecureString();
            string passwordChars = String.Empty;

            foreach (PasswordOption po in passwordOptions)
            {
                passwordChars += po.Characters;
            }

            if (string.IsNullOrEmpty(passwordChars))
                return null;

            var random = RandomSeedGenerator.GetRandom();

            for (int i = 0; i < passwordLength; i++)
            {
                int index;
                char passwordChar;
                if (!passwordOptions.AllOptionsAreUsed)
                {
                    PasswordOption po = passwordOptions.GetUnusedOption();
                    index = random.Next(po.Characters.Length);
                    passwordChar = po.Characters[index];
                }
                else
                {
                    index = random.Next(passwordChars.Length);
                    passwordChar = passwordChars[index];
                }

                securePassword.AppendChar(passwordChar);
            }

            return securePassword;
        }

        private int GetOptionsUsed()
        {
            int ret = 0;
            foreach (CharacterTypes option in Enum.GetValues(typeof(CharacterTypes)))
            {

            }
            return ret;
        }

        /// <summary>
        /// Gets the characters selected by the option
        /// </summary>
        /// <returns></returns>
        private static PasswordOptions GetCharacters(CharacterTypes option)
        {
            PasswordOptions list = new PasswordOptions();
            switch (option)
            {
                case CharacterTypes.Alpha_Lower:
                    list.Add(AlphaLC);
                    break;
                case CharacterTypes.Alpha_Upper:
                    list.Add(AlphaUC);
                    break;
                case CharacterTypes.Alpha_Upper_and_Lower:
                    list.Add(AlphaLC);
                    list.Add(AlphaUC);
                    break;
                case CharacterTypes.Digit:
                    list.Add(Digits);
                    break;
                case CharacterTypes.AlphaNumeric:
                    list.Add(AlphaLC);
                    list.Add(AlphaUC);
                    list.Add(Digits);
                    break;
                case CharacterTypes.Special:
                    list.Add(Specials);
                    break;
                case CharacterTypes.AlphaNumericSpecial:
                    list.Add(AlphaLC);
                    list.Add(AlphaUC);
                    list.Add(Digits);
                    list.Add(Specials);
                    break;
                default:
                    break;
            }
            return list;
        }
    }

    public static class RandomSeedGenerator
    {
        /// <summary>
        /// Gets a random object with a real random seed
        /// </summary>
        /// <returns></returns>
        public static Random GetRandom()
        {
            // Use a 4-byte array to fill it with random bytes and convert it then
            // to an integer value.
            byte[] randomBytes = new byte[4];

            // Generate 4 random bytes.
            RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();
            rng.GetBytes(randomBytes);

            // Convert 4 bytes into a 32-bit integer value.
            int seed = (randomBytes[0] & 0x7f) << 24 |
                        randomBytes[1] << 16 |
                        randomBytes[2] << 8 |
                        randomBytes[3];

            // Now, this is real randomization.
            return new Random(seed);
        }
    }

    public class PasswordOption
    {
        public int Count { get; set; }
        public String Characters { get; set; }
    }

    public class PasswordOptions : List<PasswordOption>
    {
        public bool AllOptionsAreUsed
        {
            get
            {
                foreach (PasswordOption po in this)
                {
                    if (po.Count < 1)
                        return false;
                }
                return true;
            }
        }

        public PasswordOption GetUnusedOption()
        {
            PasswordOptions options = new PasswordOptions();
            foreach (PasswordOption po in this)
            {
                if (po.Count < 1)
                    options.Add(po);
            }
            if (options.Count < 1)
                return null;

            var random = RandomSeedGenerator.GetRandom();
            int optionIndex = random.Next(options.Count);
            return options[optionIndex];
        }
    }

    public class InvalidPasswordLengthException : ArgumentException { }
    public class InvalidPasswordCharacterTypeException : ArgumentException { }

    public static class SecureStringExtender
    {
        public static string ConvertToPlainTextString(this SecureString securePassword)
        {
            if (securePassword == null)
                throw new ArgumentNullException("securePassword");

            IntPtr unmanagedString = IntPtr.Zero;
            try
            {
                unmanagedString = Marshal.SecureStringToGlobalAllocUnicode(securePassword);
                return Marshal.PtrToStringUni(unmanagedString);
            }
            finally
            {
                Marshal.ZeroFreeGlobalAllocUnicode(unmanagedString);
            }
        }

        public static SecureString Scramble(this SecureString securePassword)
        {
            SecureString retSS = securePassword;
            Random random = RandomSeedGenerator.GetRandom();
            int moves = random.Next(securePassword.Length, securePassword.Length * 2);
            for (int i = 0; i < moves; i++)
            {
                int origIndex = random.Next(securePassword.Length);
                int newIndex = random.Next(securePassword.Length);
                char c = retSS.GetAt(origIndex);
                retSS.InsertAt(newIndex, c);
            }
            return retSS;
        }

        public static Char GetAt(this SecureString securePassword, int index)
        {
            if (securePassword.Length < index)
                throw new ArgumentException("The index parameter must not be greater than the string's length.");
            if (index < 0)
                throw new ArgumentException("The index must be 0 or greater.");
            return securePassword.ConvertToPlainTextString().Substring(index, 1).ToCharArray()[0];
        }
    }
}

Now if you want to make a simple command line executable that uses the code above, just create a new console project and call this line:

Console.WriteLine(RandomPasswordGenerator.Generate().ConvertToPlainTextString());

I added more code to handle command line parameters.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security;

namespace ConsoleApplication2
{
    class Program
    {
        private static int PasswordLength;
        private static String Characters;

        static void Main(string[] args)
        {
            if (args.Length > 2)
            {
                ShowArgs();
                return;
            }

            if (args.Length > 0)
            {
                foreach (char c in args[0])
                {
                    if (char.IsDigit(c))
                    {
                        ShowArgs();
                        return;
                    }
                }
                PasswordLength = Convert.ToInt32(args[0]);
            }

            if (args.Length == 2)
                Characters = args[1];

            Console.WriteLine(RandomPasswordGenerator.Generate().ConvertToPlainTextString());
        }

        private static void ShowArgs()
        {
            String fullExeNameAndPath = System.Reflection.Assembly.GetExecutingAssembly().Location;
            String ExeName = System.IO.Path.GetFileName(fullExeNameAndPath);

            Console.WriteLine("Usage: " + ExeName + " [int] [string]");
            Console.WriteLine("[int] - The length of the password.  By default it is 11.");
            Console.WriteLine("[string] - The characters to use for the password.  By default it is alphanumeric case sensitive.");
        }
}

Hope you find this helpful. If you find flaws, please comment!

File access is made simple with C# (Mono) on FreeBSD.

Reading a text file with C# (Mono)

To read a file, use a StreamReader object. However, it is easy if you don’t do a new StreamWriter("File.txt") but instead use File.OpenText("File.txt") to create the StreamReader. Once you have the stream, you just need to run the stream’s ReadToEnd() function.

Here is a snippet to read a text file as a string.

// Open the file into a StreamReader
StreamReader file = File.OpenText("SomeFile.txt");
// Read the file into a string
string s = file.ReadToEnd();

Now that you have the text file as a string, you can manipulate the string as you desire.

Writing to a text file with C# (Mono)

To write a text file, use StreamWriter.

string str = "Some text";
// Hook a write to the text file.
StreamWriter writer = new StreamWriter("SomeFile.txt");
// Rewrite the entire value of s to the file
writer.Write(str);

You can also just add a line to the end of the file as follows:

string str = "Some text";
// Hook a write to the text file.
StreamWriter writer = new StreamWriter("SomeFile.txt");
// Rewrite the entire value of s to the file
writer.WriteLine(str);

Example for learning

An example of these in a little project file made with MonoDevelop.

using System;
using System.IO;

namespace FileAccess
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			string FileName="TestFile.txt";

			// Open the file into a StreamReader
			StreamReader file = File.OpenText(FileName);
			// Read the file into a string
			string s = file.ReadToEnd();
			// Close the file so it can be accessed again.
			file.Close();

			// Add a line to the text
			s  += "A new line.\n";

			// Hook a write to the text file.
			StreamWriter writer = new StreamWriter(FileName);
			// Rewrite the entire value of s to the file
			writer.Write(s);

			// Add a single line
			writer.WriteLine("Add a single line.");

			// Close the writer
			writer.Close();
		}
	}
}

Well, this should get you started.