.NET Framework Class Library
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)
Syntax
<[%$TOPIC/cey1zx63_en-us_VS_110_2_0_0_0_0%]> _
<[%$TOPIC/cey1zx63_en-us_VS_110_2_0_0_0_1%](True)> _
Public Structure Guid _
	Implements [%$TOPIC/cey1zx63_en-us_VS_110_2_0_0_0_2%], [%$TOPIC/cey1zx63_en-us_VS_110_2_0_0_0_3%], [%$TOPIC/cey1zx63_en-us_VS_110_2_0_0_0_4%](Of Guid),  _
	[%$TOPIC/cey1zx63_en-us_VS_110_2_0_0_0_5%](Of Guid)
[[%$TOPIC/cey1zx63_en-us_VS_110_2_0_1_0_0%]]
[[%$TOPIC/cey1zx63_en-us_VS_110_2_0_1_0_1%](true)]
public struct Guid : [%$TOPIC/cey1zx63_en-us_VS_110_2_0_1_0_2%], [%$TOPIC/cey1zx63_en-us_VS_110_2_0_1_0_3%], 
	[%$TOPIC/cey1zx63_en-us_VS_110_2_0_1_0_4%]<Guid>, [%$TOPIC/cey1zx63_en-us_VS_110_2_0_1_0_5%]<Guid>
[[%$TOPIC/cey1zx63_en-us_VS_110_2_0_2_0_0%]]
[[%$TOPIC/cey1zx63_en-us_VS_110_2_0_2_0_1%](true)]
public value class Guid : [%$TOPIC/cey1zx63_en-us_VS_110_2_0_2_0_2%], [%$TOPIC/cey1zx63_en-us_VS_110_2_0_2_0_3%], 
	[%$TOPIC/cey1zx63_en-us_VS_110_2_0_2_0_4%]<Guid>, [%$TOPIC/cey1zx63_en-us_VS_110_2_0_2_0_5%]<Guid>
[<[%$TOPIC/cey1zx63_en-us_VS_110_2_0_3_0_0%]>]
[<[%$TOPIC/cey1zx63_en-us_VS_110_2_0_3_0_1%]>]
[<[%$TOPIC/cey1zx63_en-us_VS_110_2_0_3_0_2%](true)>]
type Guid =  
    struct 
        interface [%$TOPIC/cey1zx63_en-us_VS_110_2_0_3_0_3%] 
        interface [%$TOPIC/cey1zx63_en-us_VS_110_2_0_3_0_4%] 
        interface [%$TOPIC/cey1zx63_en-us_VS_110_2_0_3_0_5%]<Guid>
        interface [%$TOPIC/cey1zx63_en-us_VS_110_2_0_3_0_6%]<Guid>
    end

The Guid type exposes the following members.

Constructors
  NameDescription
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps Guid(Byte)Initializes a new instance of the Guid structure by using the specified array of bytes.
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps Guid(String)Initializes a new instance of the Guid structure by using the value represented by the specified string.
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps Guid(Int32, Int16, Int16, Byte)Initializes a new instance of the Guid structure by using the specified integers and byte array.
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps Guid(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 method Guid(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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Methods
  NameDescription
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps CompareTo(Guid)Compares this instance to a specified Guid object and returns an indication of their relative values.
Public method Supported by the XNA Framework CompareTo(Object)Compares this instance to a specified object and returns an indication of their relative values.
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps Equals(Guid)Returns a value indicating whether this instance and a specified Guid object represent the same value.
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps Equals(Object)Returns a value that indicates whether this instance is equal to a specified object. (Overrides ValueTypeEquals(Object).)
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps GetHashCodeReturns the hash code for this instance. (Overrides ValueTypeGetHashCode.)
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps GetTypeGets the Type of the current instance. (Inherited from Object.)
Public method Static member Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps NewGuidInitializes a new instance of the Guid structure.
Public method Static member Supported by Portable Class Library Supported in .NET for Windows Store apps ParseConverts the string representation of a GUID to the equivalent Guid structure.
Public method Static member Supported by Portable Class Library Supported in .NET for Windows Store apps ParseExactConverts the string representation of a GUID to the equivalent Guid structure, provided that the string is in the specified format.
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps ToByteArrayReturns a 16-element byte array that contains the value of this instance.
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps ToStringReturns a string representation of the value of this instance in registry format. (Overrides ValueTypeToString.)
Public method Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps ToString(String)Returns a string representation of the value of this Guid instance, according to the provided format specifier.
Public method Supported by the XNA Framework ToString(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 method Static member Supported by Portable Class Library Supported in .NET for Windows Store apps TryParseConverts the string representation of a GUID to the equivalent Guid structure.
Public method Static member Supported by Portable Class Library Supported in .NET for Windows Store apps TryParseExactConverts the string representation of a GUID to the equivalent Guid structure, provided that the string is in the specified format.
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Operators
  NameDescription
Public operator Static member Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps EqualityIndicates whether the values of two specified Guid objects are equal.
Public operator Static member Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps InequalityIndicates whether the values of two specified Guid objects are not equal.
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Fields
  NameDescription
Public field Static member Supported by the XNA Framework Supported by Portable Class Library Supported in .NET for Windows Store apps EmptyA read-only instance of the Guid structure whose value is all zeros.
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Explicit Interface Implementations
  NameDescription
Explicit interface implemetation Private method Supported by Portable Class Library Supported in .NET for Windows Store apps IComparableCompareToCompares this instance to a specified object and returns an indication of their relative values.
Explicit interface implemetation Private method Supported by Portable Class Library Supported in .NET for Windows Store apps IFormattableToStringReturns a string representation of the value of this instance, according to the provided format specifier.
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Remarks
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.

Examples

The following example uses the System.Runtime.InteropServicesGuidAttribute 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.

Imports System.Runtime.InteropServices

' Guid for the interface IMyInterface.
<Guid("F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4")> _
Interface IMyInterface
    Sub MyMethod()
End Interface 

' Guid for the coclass MyTestClass.
<Guid("936DA01F-9ABD-4d9d-80C7-02AF85C822A8")> _
Public Class MyTestClass
    Implements IMyInterface

    Public Sub MyMethod() Implements IMyInterface.MyMethod
    End Sub 

    Public Shared Sub Main()
        Dim IMyInterfaceAttribute As GuidAttribute = CType(Attribute.GetCustomAttribute(GetType(IMyInterface), GetType(GuidAttribute)),
                                                           GuidAttribute)

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

        ' Use the string to create a guid. 
        Dim myGuid1 As New Guid(IMyInterfaceAttribute.Value)
        ' Use a byte array to create a guid. 
        Dim myGuid2 As New Guid(myGuid1.ToByteArray())

        If myGuid1.Equals(myGuid2) Then
            Console.WriteLine("myGuid1 equals myGuid2")
        Else
            Console.WriteLine("myGuid1 does not equal myGuid2")
        End If  

        ' The equality operator can also be used to determine if two guids have same value. 
        If myGuid1.ToString() = myGuid2.ToString() Then
            Console.WriteLine("myGuid1 == myGuid2")
        Else
            Console.WriteLine("myGuid1 != myGuid2")
        End If 
    End Sub 
End Class 
' The example displays the following output: 
'       IMyInterface Attribute: F9168C5E-CEB2-4faa-B6BF-329BF39FA1E4 
'       myGuid1 equals myGuid2 
'       myGuid1 == myGuid2
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
using namespace System;
using namespace System::Runtime::InteropServices;

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


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

int main()
{
   Attribute^ IMyInterfaceAttribute = Attribute::GetCustomAttribute( IMyInterface::typeid, GuidAttribute::typeid );

   // The Value property of GuidAttribute returns a string. 
   System::Console::WriteLine( String::Concat(  "IMyInterface Attribute: ", (dynamic_cast<GuidAttribute^>(IMyInterfaceAttribute))->Value ) );

   // Using the string to create a guid.
   Guid myGuid1 = Guid(dynamic_cast<GuidAttribute^>(IMyInterfaceAttribute)->Value);

   // Using a byte array to create a guid.
   Guid myGuid2 = Guid(myGuid1.ToByteArray());

   // Equals is overridden to perform a value comparison. 
   if ( myGuid1.Equals( myGuid2 ) )
      System::Console::WriteLine(  "myGuid1 equals myGuid2" );
   else
      System::Console::WriteLine(  "myGuid1 not equals 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.

Version Information

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

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

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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