Assembly: mscorlib (in mscorlib.dll)
Like Marshal.FreeCoTaskMem and Marshal.FreeHGlobal, you can use this method to deallocate memory. FreeBSTR calls SysFreeString, a COM API method, which frees memory allocated by any of the following unmanaged methods: SysAllocString, SysAllocStringByteLen, SysAllocStringLen, SysReAllocString, SysReAllocStringLen. You can call unmanaged methods such as these with platform invoke. For details, see Consuming Unmanaged DLL Functions.
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.
Windows 98, Windows 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 .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.