Unhandled Exception: System.AccessViolationException: Attempted to read or write

Question

Below is my c++ DLL

// DLL.cpp : Defines the exported functions for the DLL application.
#include "stdafx.h"
//#include <stdexcept> 
#include<iostream>
using namespace std; 

typedef void (*FunctionPtr)(int); 
void (*FunctionPtr1)(int); 
extern "C" __declspec(dllexport)void Caller();
extern "C" __declspec(dllexport)void RegisterFunction(FunctionPtr func_ptr); 


    extern void Caller() 
    {    

        int i = 10;
        FunctionPtr1(i);
 } 

    extern void RegisterFunction(FunctionPtr func_ptr1)
 {
     FunctionPtr1 = func_ptr1;

 }

This DLL will get refernce to function name from c# and pass arguments to c# function.. here is my c# code

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;



namespace test
{
    class Program
    {

        [DllImport("C:/Users/10602857/Documents/Visual Studio 2010/Projects/DLL/Debug/DLL.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern void Caller();

       [DllImport("C:/Users/10602857/Documents/Visual Studio 2010/Projects/DLL/Debug/DLL.dll", CallingConvention = CallingConvention.Cdecl)]
        public static extern fPointer  RegisterFunction(fPointer aa);

        static void Main(string[] args)
            {
                    Console.WriteLine("DLL Linking");
                    fPointer abc = new fPointer(ping);
                    RegisterFunction(abc);      //send address of function to DLL
                    Caller();                   //call from DLL
            }

        public  delegate void fPointer(int s);       // point to every functions that it has void as return value and with no input parameter 


        public static void ping(int a)
             {
                     Console.WriteLine("ping executed " + a);
             }

        public static void add1()
              {
                      Console.WriteLine("add executed");
              }

    }
}

c# code is able to get the value which i paseed in c++ dll as below

int i = 10;
        FunctionPtr1(i);

M getting the sedired output but progrram got crashed at the end with following execption

Unhandled Exception: System.AccessViolationException: Attempted to read or write
 protected memory. This is often an indication that other memory is corrupt.
   at test.Program.Caller()

why i am getting this ??

Answer 1

All i need to do is.. just declare my delegate as ...

[UnmanagedFunctionPointer(CallingConvention.Cdecl)] 
public delegate void MyDelegate();