CppAndCSharpLink

Getting Started

Pre-requisites:

Usage

Step 1: Create the C++ Library

Step 2: Add a header file YourHeaderFile.h

#pragma once
class Sample {
	int x;
public:
	Sample(int x);
	int add(int x);
	int multiply(int x);
};
// Helper methods for constructor and other method
extern "C" _declspec(dllexport) void* Instantiate(int x) {
	return (void*) new Sample(x);
}
extern "C" _declspec(dllexport) int Add(Sample* t, int y) {
	return t->add(y);
}
extern "C" _declspec(dllexport) int Multiply(Sample* t, int y) {
	return t->multiply(y);
}

Step 3: Add a C++ source file YourSourceFile.cpp

#include "pch.h"
#include "sample.h"
// Example Constructor
Sample::Sample(int x) {
	this->x = x;
}
// Example methods below
int Sample::add(int y) {
	return this->x + y;
}
int Sample::multiply(int y) {
	return this->x + y;
}

Step 4: Adjust Visual Studio Configuration Settings

Step 5: Build the C++ project.

Step 6: Create a C# Project

Step 7: Include Relevant namespaces to C# project

// Write this code on top of your c# source file
using System.Runtime.InteropServices;

Step 8: Include Relevant namespaces to C# project

1. Create a wrapper class to encapsulate all the dll methods
2. Declare the C++ function you want to call using the DllImport attribute. 
3. Specify the name of the C++ DLL and the calling convention (CallingConvention.Cdecl for C++).
4. Define some C# methods that wraps the import c++ functions
public static class WrapperClass
{
 #region dllImports
 // Target the cpp dll here -- add project reference to this dll in C# project also
 private const string _dllImportPath = @"filePathofYourDll";
 // Declare the C++ function you want to call using the DllImport attribute.
 // Specify the name of the C++ DLL and the calling convention (CallingConvention.Cdecl for C++).
 [DllImport(_dllImportPath, CallingConvention = CallingConvention.Cdecl)]
 public static extern IntPtr Instantiate(int x);
 [DllImport(_dllImportPath, CallingConvention = CallingConvention.Cdecl)]
 public static extern int Add(IntPtr t, int y);
 [DllImport(_dllImportPath, CallingConvention = CallingConvention.Cdecl)]
 public static extern int Multiply(IntPtr t, int y);
 #endregion
}

Step 9: Call the C++ function using the wrapper methods in a separate main class

public class Program
{
 public static void Main(string[] args)
 {
 #region callDllMethods
 IntPtr i = WrapperClass.Instantiate(2);
 int total = WrapperClass.Add(i, 3);
 int total2 = WrapperClass.Multiply(i, 10);
 Console.WriteLine("Total Add method: " + total + ", Total Multiply method: " + total2);
 #endregion
 }
}

Step 10: Build and run your C# project

Note