Passing c# string to unmanaged c++ DLL

Question

I have a simple application that loads an unmanaged dll and passes a few string values to it from C#. But in the C++ dll application, I receive an exception :: Tried to access a read/write protected memory. My DLL Import looks like this: ``` [DllImport("X.dll", CallingConvention = CallingConvention.Cdecl) ] public static extern int DumpToDBLogFile([MarshalAs(UnmanagedType.I4)]int loggingLevel, [MarshalAs(UnmanagedType.I4)]int jobId, int threadId, [MarshalAs(UnmanagedType.LPStr)]string procName, [MarshalAs(UnmanagedType.LPStr)]string message); ``` and the C++ Declaration is like ``` extern "C" __declspec(dllexport) int DumpToDBLogFile( int loggingLevel, int jobId, int threadId, string procName, string message ) { //access strings.. } ``` Help please!!!

Accepted Answer

```
string != LPStr
```

try:

```
extern "C"
__declspec(dllexport) int DumpToDBLogFile( int loggingLevel, int jobId, int threadId, char* procName, char* message ) { //access strings..

}
```

Passing c# string to unmanaged c++ DLL

Solution

Problem