This documentation is archived and is not being maintained.

Marshal.StringToCoTaskMemAuto Method

Copies the contents of a managed String to a block of memory allocated from the unmanaged COM task allocator.

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

public static IntPtr StringToCoTaskMemAuto(
	string s


Type: System.String
A managed string to be copied.

Return Value

Type: System.IntPtr
The allocated memory block, or 0 if s is null.


There is insufficient memory available.


The length for s is out of range.

StringToCoTaskMemAuto is useful for custom marshaling or for use when mixing managed and unmanaged code. Because this method allocates the unmanaged memory required for a string, always free the memory by calling FreeCoTaskMem. This method provides the opposite functionality of Marshal.PtrToStringAuto.

The characters of the string are copied as either ANSI or Unicode characters, depending on the operating system where the code is executing. On Windows 98, the characters are copied as ANSI characters. On Windows NT 4.0, Windows 2000, Windows XP, and the Windows Server 2003 family, the characters are copied as Unicode characters.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

  • SecurityCriticalAttribute 

    requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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