您不能元帅的CString ，因为它不是一个原生型 - 这是一个封装了一个C ++类一个字符阵列。

You can't marshal CString as it's not a native type - it's a C++ class that wraps up a char array.

您可以名帅字符串到的char [] 为的char [] 是本机类型。你需要有参数到你想要的功能的P / Invoke为基本类型，如 INT ，布尔， 字符或结构，而不是类。在这里阅读更多：

You can marshal string to char[] as char[] is a native type. You need to have the parameters to the function you want to P/Invoke into as basic types like int, bool, char or struct, but not classes. Read more here:

http://msdn.microsoft.com/en-us/library/ aa446536.aspx

为了调用该采取的CString作为参数的函数，你可以做这样的事情：

In order to call functions that take CString as an argument you can do something like this:

//Compile with /UNICODE
extern "C" MFCINTEROP_API int GetStringLen(const TCHAR* str) {
  CString s(str);
  return s.GetLength();
  //Or call some other function taking CString as an argument
  //return CallOtherFunction(s);
}

[DllImport("YourDLL.dll", CharSet=CharSet.Unicode)]
public extern static int GetStringLen(string param);        

在我们传递了一个 System.String 可调集到的char * / wchar_t的* $ C $上面的P / Invoke函数C>。非托管函数然后创建的CString 的实例，并与这一点。

In the above P/Invoke function we pass in a System.String which can marshal to char*/wchar_t*. The unmanaged function then creates a instance of CString and works with that.

在默认情况下 System.String 被编组为的char * ，所以要小心什么样的字符串的非托管的版本需要。此版本使用 TCHAR ，变成 wchar_t的在与 / UNI code编译。这就是为什么你需要指定字符集= CharSet.Uni code 在的DllImport 属性。

By default System.String is marshalled to char*, so be careful with what kind of string the unmanaged version takes. This version uses TCHAR, which becomes wchar_t when compiled with /UNICODE. That's why you need to specify CharSet=CharSet.Unicode in the DllImport attribute.