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Marshal Class

Provides a collection of methods for allocating unmanaged memory, copying unmanaged memory blocks, and converting managed to unmanaged types, as well as other miscellaneous methods used when interacting with unmanaged code.

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

public static class Marshal

The static methods defined on the Marshal class are essential to working with unmanaged code. Most methods defined in this class are typically used by developers who need to provide a bridge between the managed and unmanaged programming models. For example, the StringToHGlobalAnsi method copies ANSI characters from a specified string (in the managed heap) to a buffer in the unmanaged heap. It also allocates the target heap of the right size.

The common language runtime provides specific marshaling capabilities. For details on marshaling behavior, see Interop Marshaling.

The Read and Write methods in the Marshal class support both aligned and unaligned access.

The following code example shows how to use various methods defined by the Marshal class.

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

public struct Point
    public Int32 x, y;

public sealed class App
    static void Main()
        // Demonstrate the use of public static fields of the Marshal class.
        Console.WriteLine("SystemDefaultCharSize={0}, SystemMaxDBCSCharSize={1}",
            Marshal.SystemDefaultCharSize, Marshal.SystemMaxDBCSCharSize);

        // Demonstrate the use of the SizeOf method of the Marshal class.
        Console.WriteLine("Number of bytes needed by a Point object: {0}", 
        Point p = new Point();
        Console.WriteLine("Number of bytes needed by a Point object: {0}",

        // Demonstrate how to call GlobalAlloc and  
        // GlobalFree using the Marshal class.
        IntPtr hglobal = Marshal.AllocHGlobal(100);

        // Demonstrate how to use the Marshal class to get the Win32 error  
        // code when a Win32 method fails.
        Boolean f = CloseHandle(new IntPtr(-1));
        if (!f)
            Console.WriteLine("CloseHandle call failed with an error code of: {0}", 

    // This is a platform invoke prototype. SetLastError is true, which allows  
    // the GetLastWin32Error method of the Marshal class to work correctly.    
    [DllImport("Kernel32", ExactSpelling = true, SetLastError = true)]
    static extern Boolean CloseHandle(IntPtr h);


// This code produces the following output. 
// SystemDefaultCharSize=2, SystemMaxDBCSCharSize=1 
// Number of bytes needed by a Point object: 8 
// Number of bytes needed by a Point object: 8 
// CloseHandle call failed with an error code of: 6


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

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0