C#调用C++ 的DLL传送和接收中文字符串

1 c#向c++传送中文字符串

设置：将 字符集 改为 使用多字节字符集

cpp代码：

extern "C"_declspec(dllexport) int input_chn_str(char in_str[])
{
	cout<<in_str<<endl;
	return 0;
}
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c#代码：

[DllImport("Demo.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.Cdecl)]
public static extern bool input_chn_str(byte[] in_str);

string str = "中国chn123"; 
int rst = input_chn_str(Encoding.Default.GetBytes(str));
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2 C#接收c++返回的中文字符串

cpp代码：

extern "C"_declspec(dllexport) int ProcessChineseString(const char* input, char* output)
{
	std::string inputString(input);
	std::string outputString = "输入内容为：" + inputString;
	strcpy(output, outputString.c_str());

	return 0;
}
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c#代码：

[DllImport("ocr_cpu.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
extern static int ProcessChineseString(IntPtr input1, IntPtr output1);

string chineseInput = "你好123abc不不不";
byte[] inputBytes = Encoding.Default.GetBytes(chineseInput);
IntPtr inputPtr = Marshal.AllocHGlobal(inputBytes.Length + 1);
Marshal.Copy(inputBytes, 0, inputPtr, inputBytes.Length);
Marshal.WriteByte(inputPtr, inputBytes.Length, 0); // 添加字符串结束符

IntPtr outputPtr = Marshal.AllocHGlobal(1000);
ProcessChineseString(inputPtr, outputPtr);
string outputString = Marshal.PtrToStringAnsi(outputPtr);

Console.WriteLine(outputString);

Marshal.FreeHGlobal(inputPtr);
Marshal.FreeHGlobal(outputPtr);
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如果遇到乱码：

[DllImport("ocr_cpu.dll", CharSet = CharSet.Unicode, CallingConvention = CallingConvention.Cdecl)]
        extern static int infer(IntPtr output);


IntPtr outputPtr = Marshal.AllocHGlobal(1000);

rst = infer(outputPtr);

 {
     int length = 0;//循环查找字符串的长度 

     while (Marshal.ReadByte(outputPtr + length) != 0)
     {
         length++;
     }

     byte[] strbuf = new byte[length];
     Marshal.Copy(outputPtr, strbuf, 0, length);

     // Taken from https://msdn.microsoft.com/it-it/library/system.text.encodinginfo.getencoding(v=vs.110).aspx 
     string message1 = Encoding.UTF8.GetString(strbuf);
     Console.WriteLine(message1);
 }
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