StringToHGlobalAnsi is useful for custom marshaling or when mixing managed and unmanaged code. Since this method allocates the unmanaged memory required for a string, always free the memory by calling FreeHGlobal. StringToHGlobalAnsi provides the opposite functionality of Marshal..::.PtrToStringAnsi.

Note:

This method uses SecurityAction..::.LinkDemand to prevent it from being called from untrusted code; only the immediate caller is required to have SecurityPermissionAttribute..::.UnmanagedCode permission. If your code can be called from partially trusted code, do not pass user input to Marshal class methods without validation. For important limitations on using the LinkDemand member, see Demand vs. LinkDemand.

The following code 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::StringToHGlobalAnsi(managedString ).ToPointer();

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

    return 0;
}

• SecurityPermission 

  for permission to call unmanaged code.

  Associated enumeration: UnmanagedCode Security action: LinkDemand

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

.NET Framework

Reference