Marshal.StringToHGlobalAnsi(String) 方法

定義

命名空間:

System.Runtime.InteropServices

組件:

System.Runtime.InteropServices.dll

來源:

Marshal.cs

將 Managed String 的內容複製到 Unmanaged 記憶體中，並在它複製時轉換成 ANSI 格式。

public:
 static IntPtr StringToHGlobalAnsi(System::String ^ s);

public static IntPtr StringToHGlobalAnsi (string? s);

static member StringToHGlobalAnsi : string -> nativeint

Public Shared Function StringToHGlobalAnsi (s As String) As IntPtr

參數

s

String

要複製的 Managed 字串。

傳回

IntPtr

nativeint

Unmanaged 記憶體中複製 s 的目的位址，如果 s 為 null 則為 0。

例外狀況

OutOfMemoryException

可用的記憶體不足。

ArgumentOutOfRangeException

s 參數超過作業系統所允許的最大長度。

範例

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

StringToHGlobalAnsi 適用於自定義封送處理，或在混合 Managed 和 Unmanaged 程式代碼時使用。 因為這個方法會配置字串所需的 Unmanaged 記憶體，所以一律呼叫 FreeHGlobal來釋放記憶體。 StringToHGlobalAnsi 提供的相反功能 Marshal.PtrToStringAnsi。

這個方法會複製內嵌的 Null 字元，並包含終止的 Null 字元。

另請參閱

• FreeCoTaskMem(IntPtr)
• PtrToStringAnsi(IntPtr)