為什麼我不能在發布版本中將 char* 字元串從 C++ 返回到 C#？

我正在嘗試從 C# 呼叫以下瑣碎的 C 函式：

SIMPLEDLL_API const char* ReturnString()
{
   return "Returning a static string!";
}

使用以下 P/Invoke 聲明（有或沒有 return 屬性，沒有區別）：

[DllImport("SimpleDll")]
[return: MarshalAs(UnmanagedType.LPStr)]
public static extern string ReturnString();

如果 DLL 是 Debug 版本但在 Release 版本中崩潰 (AccessViolationException)，則它可以工作。

我正在呼叫其他十幾個簡單的函式，這是唯一一個失敗的函式（這是其他函式：）

[DllImport("SimpleDll")] public static extern int NextInt();
[DllImport("SimpleDll")] public static extern void SetNextInt(int x);
[DllImport("SimpleDll")] public static extern int AddInts(int a, int b);
[DllImport("SimpleDll")] public static extern int AddFourInts(int a, int b, int c, int d);
[DllImport("SimpleDll")] public static extern double AddDoubles(double x, double y);
[DllImport("SimpleDll")] public static extern IntPtr AddDoublesIndirect(ref double x, ref double y);
[DllImport("SimpleDll")] [return: MarshalAs(UnmanagedType.U1)]
public static extern char CharStringArgument([MarshalAs(UnmanagedType.LPStr)]string s);
[DllImport("SimpleDll")] [return: MarshalAs(UnmanagedType.U2)]
public static extern char WCharStringArgument([MarshalAs(UnmanagedType.LPWStr)]string s);
[DllImport("SimpleDll")] [return: MarshalAs(UnmanagedType.LPWStr)]
public static extern string ReturnWString();
[DllImport("SimpleDll")] [return: MarshalAs(UnmanagedType.BStr)]
public static extern string ReturnBSTR();
[DllImport("SimpleDll")] public static extern System.Drawing.Point MakePoint(int x, int y);
[DllImport("SimpleDll")] public static extern IntPtr MakePointIndirect(int x, int y);
[DllImport("SimpleDll")] public static extern int GetPointY(System.Drawing.Point p);
[DllImport("SimpleDll")] public static extern int GetPointYIndirect(ref System.Drawing.Point pp);
[DllImport("SimpleDll")] public static extern int SumIntegers(ref int firstElem, int size);

或者也許嘗試使用

[DllImport("SimpleDll")]
public static extern IntPtr ReturnString();

並在您的呼叫程式碼中，使用 Marshal Class

string ret = System.Runtime.InteropServices.Marshal.PtrToStringAnsi(PInvoke.ReturnString());

引用自：https://stackoverflow.com/questions/6300093