How to call on a function found on another file?

Question

I'm recently starting to pick up C++ and the SFML library, and I was wondering if I defined a Sprite on a file appropriately called "player.cpp" how would I call it on my main loop located at "main.cpp"?

Here is my code (Be aware that this is SFML 2.0, not 1.6!).

main.cpp

#include "stdafx.h"
#include <SFML/Graphics.hpp>
#include "player.cpp"

int main()
{
    sf::RenderWindow window(sf::VideoMode(800, 600), "Skylords - Alpha v1");

    while (window.isOpen())
    {
        sf::Event event;
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                window.close();
        }

        window.clear();
        window.draw();
        window.display();
    }

    return 0;
}

player.cpp

#include "stdafx.h"
#include <SFML/Graphics.hpp>

int playerSprite(){
    sf::Texture Texture;
    if(!Texture.loadFromFile("player.png")){
        return 1;
    }
    sf::Sprite Sprite;
    Sprite.setTexture(Texture);
    return 0;
}

Where I need help is in the main.cpp where it says window.draw(); in my draw code. In that parenthesis, there should be the name of the Sprite that I want to load onto the screen. As far as I've searched, and tried by guessing, I have not succeeded into making that draw function work with my sprite on the other file. I feel like I'm missing something big, and very obvious (on either files), but then again, every pro was once a newb.

Answer 1

You can use header files.

Good practice.

You can create a file called player.h declare all functions that are need by other cpp files in that header file and include it when needed.

player.h

#ifndef PLAYER_H    // To make sure you don't declare the function more than once by including the header multiple times.
#define PLAYER_H

#include "stdafx.h"
#include <SFML/Graphics.hpp>

int playerSprite();

#endif

player.cpp

#include "player.h"  // player.h must be in the current directory. or use relative or absolute path to it. e.g #include "include/player.h"

int playerSprite(){
    sf::Texture Texture;
    if(!Texture.loadFromFile("player.png")){
        return 1;
    }
    sf::Sprite Sprite;
    Sprite.setTexture(Texture);
    return 0;
}

main.cpp

#include "stdafx.h"
#include <SFML/Graphics.hpp>
#include "player.h"            //Here. Again player.h must be in the current directory. or use relative or absolute path to it.

int main()
{
    // ...
    int p = playerSprite();  
    //...

---

Not such a good practice but works for small projects. declare your function in main.cpp

#include "stdafx.h"
#include <SFML/Graphics.hpp>
// #include "player.cpp"


int playerSprite();  // Here

int main()
{
    // ...   
    int p = playerSprite();  
    //...

Answer 2

Small addition to @user995502's answer as to how to run the program.

g++ player.cpp main.cpp -o main.out && ./main.out

Answer 3

Your sprite is created mid way through the playerSprite function... it also goes out of scope and ceases to exist at the end of that same function. The sprite must be created where you can pass it to playerSprite to initialize it and also where you can pass it to your draw function.

Perhaps declare it above your first while?