Visual C++: Extracting event handler to .cpp file

Question

As a php developer, after doing a lot of algorithmic c++ excercises I've decided to start learning Visual C++. Just after getting started I am stuck on something pretty basic. I am trying to extract Button-click event to my .cpp file from .h file.

My .h file:

#pragma once

namespace Project1 {
...
    this->button2->Click += gcnew System::EventHandler(this, &MyForm::button2_Click);
...
}

In my .cpp file I've tried to do so:

#include "MyForm.h"
using namespace System;
using namespace System::Windows::Forms;
namespace Project1 {
    [STAThread]
    void main(array<String^>^ args)
    {

        void MyForm::button2_Click(System::Object^  sender, System::EventArgs^  e) {
            // definition
        }
...
}

It does not work. It says that Project1::MyForm doesnt have button2_Click. What am I missing?

Answer 1

Standard 'learning the language' warning: This isn't C++ you're writing, it's C++/CLI. C++/CLI is a language from Microsoft intended to allow C# or other .Net languages to interface with standard C++. In that scenario, C++/CLI can provide the translation between the two. If you're still learning C++, please do not start with C++/CLI. In order to effectively write in C++/CLI, one should already know both C++ and C#, and then there's still things to learn about C++/CLI. If you want to learn C++, stick with standard (unmanaged) C++. (In Visual Studio, create a "Win32" C++ project.) If you want to learn managed code, then I would use C#.

---

void main(array<String^>^ args)
{
    void MyForm::button2_Click(System::Object^  sender, System::EventArgs^  e) {
        // definition
    }
}

That's not how you define methods: You've got the definition for one method inside the definition of another method, and that's not allowed.

What you would need to do here is to declare the button2_Click method in MyForm.h, and have its implementation in MyForm.cpp

// MyForm.h
public ref class MyForm : System::Windows::Forms::Form
{
    // Lots of other stuff...
private:
    void button2_Click(System::Object^ sender, System::EventArgs^ e);
}

.

// MyForm.cpp
#include "MyForm.h"

void MyForm::button2_Click(System::Object^ sender, System::EventArgs^ e)
{
    // definition
}