释放以前从进程的非托管内存中分配的内存。

命名空间: System.Runtime.InteropServices
程序集: mscorlib（位于 mscorlib.dll）

下面的示例演示如何将托管的内容转换 String 类写入非托管内存，并因而释放非托管内存完成。

using System;
using System.Runtime.InteropServices;
class MainFunction
    static void Main()
    Console.WriteLine("\nStringToGlobalAnsi\n");
    // Create a managed string.
    String  managedString = "I am a managed String";
    Console.WriteLine("1) managedString = " + managedString );
    // Marshal the managed string to unmanaged memory.
    IntPtr stringPointer = (IntPtr)Marshal.StringToHGlobalAnsi(managedString);
    Console.WriteLine("2) stringPointer = {0}", stringPointer );
    // Get the string back from unmanaged memory
    String RetrievedString = Marshal.PtrToStringAnsi( stringPointer);
    Console.WriteLine("3) Retrieved from unmanaged memory = " + RetrievedString );
    // Always free the unmanaged string.
    Marshal.FreeHGlobal(stringPointer);
    // IntPtr handle value is still the same:
    Console.WriteLine("4) stringPointer = " + stringPointer );
    // However, it contains no data after being freed:
    String RetrievedString2 = Marshal.PtrToStringAnsi( stringPointer);
    Console.WriteLine("5) RetrievedString2 = " + RetrievedString2 );