Question

I’m currently learning SDL for creating graphical applications/games in C++ and have a few questions about how you create and use voids within classes.

For my current project I’m creating a very basic pong game and would like to create a class that not only contains information about an object’s position, loaded bitmap and other variables but also a function that covers the AI/Movement Engine and another for the rendering.

I would like to code it so that I could format my code like this:
(All code below is pseudo code and only represents the structure of what I want to achieve)

class Object
{
    private int stuff;
    private void manageStuff();
}

void Object::manageStuff()
{
    stuff++;
}

Object object = new Object();

object.stuff = 0;

for (int i = 0; i < 10, i++)
{
    object.manageStuff();
    cout << object.stuff;
}

Are there any obvious ways of doing this in C++?

Answer 1

I think you’re looking for constructors and initalizer lists. There are a number of other issues in the example you showed too, which I’ve fixed and commented in place. Perhaps:

#include <iostream>

class Object
{
// Note: access modifier written like this:
public:
    int stuff;
    void manageStuff();
    Object(); // Constructor which takes no arguments
}; // note semicolon

void Object::manageStuff()
{
    stuff++;
}

Object::Object() : stuff(0) {
  // sets stuff to 0 upon initalization.  
  // could also have written:
  // stuff=0;
  // but in this case initalization is nicer.
}

Object object; // no need for new here

// initial value of stuff set via constructor now,
// you can't just write random statements anywhere

int main() {
  for (int i = 0; i < 10; i++) // note semicolon not comma
  {
      // if these were private this would fail:
      object.manageStuff();
      std::cout << object.stuff << "\n"; 
  }
}

Is more like what you were looking for.