Marshal.StringToHGlobalUni Method

Copies the contents of a managed String into unmanaged memory.

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

Public Shared Function StringToHGlobalUni ( _
	s As String _
) As IntPtr
Dim s As String
Dim returnValue As IntPtr

returnValue = Marshal.StringToHGlobalUni(s)
public static IntPtr StringToHGlobalUni (
	String s
public static function StringToHGlobalUni (
	s : String
) : IntPtr
Not applicable.



A managed string to be copied.

Return Value

The address, in unmanaged memory, to where the s was copied, or 0 if a null string was supplied.

Exception typeCondition


The method could not allocate enough native heap memory.


The s parameter exceeds the maximum length allowed by the operating system.

StringToHGlobalUni is useful for custom marshaling or for use when mixing managed and unmanaged code. Since 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.PtrToStringUni.


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.

    return 0;

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, 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

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