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 ref class Marshal abstract sealed
public final class Marshal
public final class Marshal
Not applicable.

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

using namespace System;
using namespace System::Runtime::InteropServices;

public value struct Point
    property int X;
    property int Y;
extern bool CloseHandle(IntPtr h);

int main()
    // Demonstrate the use of public static fields of the Marshal
    // class.

    // Demonstrate the use of the SizeOf method of the Marshal
    // class.
    Console::WriteLine("Number of bytes needed by a Point object: {0}",
    Point 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.
    bool isCloseHandleSuccess = CloseHandle(IntPtr(-1));
    if (!isCloseHandleSuccess)
            "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)]
extern bool 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 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0