Marshal.FreeHGlobal(IntPtr) 方法

定義

命名空間:

System.Runtime.InteropServices

組件:

System.Runtime.InteropServices.dll

來源:

Marshal.Unix.cs

從處理序的 Unmanaged 記憶體釋放先前配置的記憶體。

public:
 static void FreeHGlobal(IntPtr hglobal);

public static void FreeHGlobal (IntPtr hglobal);

static member FreeHGlobal : nativeint -> unit

Public Shared Sub FreeHGlobal (hglobal As IntPtr)

參數

hglobal

IntPtr

nativeint

由對 AllocHGlobal(IntPtr) 的原始相應呼叫傳回的控制代碼。

範例

下列程式碼範例示範如何呼叫 FreeHGlobal 方法。 此程式代碼範例是提供給 類別之較大範例的 Marshal 一部分。

// Demonstrate how to call GlobalAlloc and 
// GlobalFree using the Marshal class.
IntPtr hglobal = Marshal::AllocHGlobal(100);
Marshal::FreeHGlobal(hglobal);

// Demonstrate how to call GlobalAlloc and
// GlobalFree using the Marshal class.
IntPtr hglobal = Marshal.AllocHGlobal(100);
Marshal.FreeHGlobal(hglobal);

' Demonstrate how to call GlobalAlloc and 
' GlobalFree using the Marshal class.
Dim hglobal As IntPtr = Marshal.AllocHGlobal(100)
Marshal.FreeHGlobal(hglobal)

下列範例示範如何將 Managed String 類別的內容轉換為 Unmanaged 記憶體，然後在完成時處置 Unmanaged 記憶體。

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

#include <iostream>                                                 // for printf


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();

    printf("stringPointer = %s\n", stringPointer);

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

    return 0;
}

using System;
using System.Runtime.InteropServices;
using System.Threading;

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, the data may be cleared after the memory is freed, depending on whether the memory allocated to stringPointer
        // has been reclaimed or not. Uncommenting the following line (Thread.Sleep(1000)) increases the likelihood of the memory being reclaimed.
        // Thread.Sleep(1000);
        String RetrievedString2 = Marshal.PtrToStringAnsi(stringPointer);
        Console.WriteLine("5) RetrievedString2 = " + RetrievedString2);
    }
}

備註

您可以使用 FreeHGlobal 從、 ReAllocHGlobal或任何對等 Unmanaged API 方法設定的AllocHGlobal全域堆積釋放任何記憶體。 hglobal如果 參數是 IntPtr.Zero 方法，則不會執行任何動作。

FreeHGlobal 會從 Kernel32.DLL 公開 LocalFree 函式，以釋放所有位元組，讓您無法再使用 所指向的 hglobal記憶體。

除了 FreeHGlobal之外，類別 Marshal 還提供兩個其他記憶體解除分配 API 方法： DestroyStructure 和 FreeCoTaskMem。

另請參閱

• AllocHGlobal(IntPtr)
• ReAllocHGlobal(IntPtr, IntPtr)