C#调用C++的Dll(参数和返回值為char* TCHAR*)

想要在C#和C++之间进行字符串传递会涉及到两件事情:

1.C#的string和C++的字符串首指针要怎么对应.  

2.字符串分为ANSI和UNICODE.

C++ 头文件接口:

//FilePolice.h //參數和返回值為Ansi extern "C" __declspec(dllexport) char* __stdcall EncryptString(char* in_string); //參數和返回值為Unicode extern "C" __declspec(dllexport) TCHAR* __stdcall EncryptStringW(TCHAR* in_string); //參數和返回值為int extern "C" __declspec(dllexport) int __stdcall Sum(int a, int b); C++ 实现部分:

// FilePolice.cpp #include "stdafx.h" #include "FilePolice.h" TCHAR* __stdcall EncryptStringW(TCHAR* in_string) { return in_string; } char* __stdcall EncryptString(char* in_string) { return in_string; } int __stdcall Sum(int a, int b) { return a + b; }

C# 调用部分:

class Program { [DllImport("FilePolice")] public static extern int Sum(int a, int b); [DllImport("FilePolice", CallingConvention = CallingConvention.Cdecl)] [DllImport("FilePolice", CallingConvention = CallingConvention.StdCall)] UnmanagedType.LPStr 為 ANSI UnmanagedType.LPWStr 為 Unicode [DllImport("FilePolice", CharSet = CharSet.Unicode)] public static extern IntPtr EncryptStringW([MarshalAs(UnmanagedType.LPWStr)]string inString); [DllImport("FilePolice", CharSet = CharSet.Ansi)] public static extern IntPtr EncryptString([MarshalAs(UnmanagedType.LPStr)]string inString); static void Main(string[] args) { int result = Sum(1, 2); Console.WriteLine(result.ToString()); //Unicode IntPtr ip = EncryptStringW("Hello 您好."); string strIP = Marshal.PtrToStringUni(ip); Console.WriteLine(strIP); //Ansi ip = EncryptString("Hello 您好."); strIP = Marshal.PtrToStringAnsi(ip); Console.WriteLine(strIP); Console.ReadLine(); } }

为了C#能方便调用,在C++中特别将调用方式设置为:__stdcall . (关于调用方式的详细说明,请进 传送门). 否则需要在C#里指定 [DllImport("FilePolice", CallingConvention = CallingConvention.Cdecl)].

另外,由于我们的字符串中会使用到中文,所以一般使用Unicode的方式进行传递.