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Guid Structure
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Guid Structure

Represents a globally unique identifier (GUID).

To browse the .NET Framework source code for this type, see the Reference Source.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

[SerializableAttribute]
[ComVisibleAttribute(true)]
public struct Guid : IFormattable, IComparable, 
	IComparable<Guid>, IEquatable<Guid>

The Guid type exposes the following members.

  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGuid(Byte[])Initializes a new instance of the Guid structure by using the specified array of bytes.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGuid(String)Initializes a new instance of the Guid structure by using the value represented by the specified string.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGuid(Int32, Int16, Int16, Byte[])Initializes a new instance of the Guid structure by using the specified integers and byte array.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGuid(Int32, Int16, Int16, Byte, Byte, Byte, Byte, Byte, Byte, Byte, Byte)Initializes a new instance of the Guid structure by using the specified integers and bytes.
Public methodGuid(UInt32, UInt16, UInt16, Byte, Byte, Byte, Byte, Byte, Byte, Byte, Byte)Initializes a new instance of the Guid structure by using the specified unsigned integers and bytes.
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  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryCompareTo(Guid)Compares this instance to a specified Guid object and returns an indication of their relative values.
Public methodSupported by the XNA FrameworkCompareTo(Object)Compares this instance to a specified object and returns an indication of their relative values.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryEquals(Guid)Returns a value indicating whether this instance and a specified Guid object represent the same value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryEquals(Object)Returns a value that indicates whether this instance is equal to a specified object. (Overrides ValueType.Equals(Object).)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetHashCodeReturns the hash code for this instance. (Overrides ValueType.GetHashCode().)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryNewGuidInitializes a new instance of the Guid structure.
Public methodStatic memberSupported by Portable Class LibraryParseConverts the string representation of a GUID to the equivalent Guid structure.
Public methodStatic memberSupported by Portable Class LibraryParseExactConverts the string representation of a GUID to the equivalent Guid structure, provided that the string is in the specified format.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryToByteArrayReturns a 16-element byte array that contains the value of this instance.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryToString()Returns a string representation of the value of this instance in registry format. (Overrides ValueType.ToString().)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryToString(String)Returns a string representation of the value of this Guid instance, according to the provided format specifier.
Public methodSupported by the XNA FrameworkToString(String, IFormatProvider)Returns a string representation of the value of this instance of the Guid class, according to the provided format specifier and culture-specific format information.
Public methodStatic memberSupported by Portable Class LibraryTryParseConverts the string representation of a GUID to the equivalent Guid structure.
Public methodStatic memberSupported by Portable Class LibraryTryParseExactConverts the string representation of a GUID to the equivalent Guid structure, provided that the string is in the specified format.
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  NameDescription
Public operatorStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryEqualityIndicates whether the values of two specified Guid objects are equal.
Public operatorStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryInequalityIndicates whether the values of two specified Guid objects are not equal.
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  NameDescription
Public fieldStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryEmptyA read-only instance of the Guid structure whose value is all zeros.
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  NameDescription
Explicit interface implemetationPrivate methodSupported by Portable Class LibraryIComparable.CompareToCompares this instance to a specified object and returns an indication of their relative values.
Explicit interface implemetationPrivate methodSupported by Portable Class LibraryIFormattable.ToStringReturns a string representation of the value of this instance, according to the provided format specifier.
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NoteNote

To view the .NET Framework source code for this type, see the Reference Source. You can browse through the source code online, download the reference for offline viewing, and step through the sources (including patches and updates) during debugging; see instructions.

A GUID is a 128-bit integer (16 bytes) that can be used across all computers and networks wherever a unique identifier is required. Such an identifier has a very low probability of being duplicated.

The following example uses the System.Runtime.InteropServices.GuidAttribute class to assign a GUID to an interface and to a user-defined class. It retrieves the value of the GUID by calling the GetCustomAttribute method, and compares it with two other GUIDs to determine whether they are equal.

using System;
using System.Runtime.InteropServices;

// Guid for the interface IMyInterface.
[Guid("F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4")]
interface IMyInterface
{
    void MyMethod();
}

// Guid for the coclass MyTestClass.
[Guid("936DA01F-9ABD-4d9d-80C7-02AF85C822A8")]
public class MyTestClass : IMyInterface
{
    public void MyMethod() {}

    public static void Main( string []args )
    {
        GuidAttribute IMyInterfaceAttribute = (GuidAttribute) Attribute.GetCustomAttribute(typeof(IMyInterface), typeof(GuidAttribute));

        System.Console.WriteLine("IMyInterface Attribute: " + IMyInterfaceAttribute.Value );    

        // Use the string to create a guid.
        Guid myGuid1 = new Guid(IMyInterfaceAttribute.Value );
        // Use a byte array to create a guid.
        Guid myGuid2 = new Guid(myGuid1.ToByteArray());

        if (myGuid1.Equals(myGuid2))
            System.Console.WriteLine("myGuid1 equals myGuid2");
        else
            System.Console.WriteLine("myGuid1 does not equal myGuid2" );

        // Equality operator can also be used to determine if two guids have same value. 
        if ( myGuid1 == myGuid2 )
            System.Console.WriteLine( "myGuid1 == myGuid2" );
        else
            System.Console.WriteLine( "myGuid1 != myGuid2" );
    }
}
// The example displays the following output: 
//       IMyInterface Attribute: F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4 
//       myGuid1 equals myGuid2 
//       myGuid1 == myGuid2

Note that the GuidAttribute attribute is typically used in an application to expose a type to COM. If you compile this example, you can run the Assembly Registration tool (Regasm.exe) on the generated assembly to create registry (.reg) and type library (.tlb) files. The .reg file can be used to register the coclass in the registry, and the .tlb file can provide metadata for COM interop.

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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