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MSDN Library

Marshal.StringToHGlobalAuto Method

Copies the contents of a managed String into unmanaged memory, converting into ANSI format if required.

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

public static IntPtr StringToHGlobalAuto(
	string s
)

Parameters

s
Type: System.String

A managed string to be copied.

Return Value

Type: System.IntPtr
The address, in unmanaged memory, to where the string was copied, or 0 if s is null.

ExceptionCondition
OutOfMemoryException

There is insufficient memory available.

StringToHGlobalAuto 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 FreeHGlobal. This method provides the opposite functionality of Marshal.PtrToStringAuto.

This method copies embedded null characters, and includes a terminating null character.

The following example demonstrates how to convert the contents of a managed String class to unmanaged memory and then dispose of the unmanaged memory when done.

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

int main()
{
    // Create a managed string.
    String^ managedString = "Hello unmanaged world (from the managed world).";

    // Marshal the managed string to unmanaged memory. 
    char*  stringPointer = (char*) Marshal::StringToHGlobalAuto(managedString).ToPointer();

    // Pass the string to an unmanaged API. 

    // Always free the unmanaged string.
    Marshal::FreeHGlobal(IntPtr(stringPointer));

    return 0;
}

.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

  • SecurityCriticalAttribute 

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

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