Problems grasping .h files...

This is a discussion on Problems grasping .h files... within the C++ Programming forums, part of the General Programming Boards category; Decided to make a RPG Adventure game using Allegro and C++ and I want to split my files up. Here's ...

  1. #1
    Registered User FoFGhost's Avatar
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    Unhappy Problems grasping .h files...

    Decided to make a RPG Adventure game using Allegro and C++ and I want to split my files up. Here's what I would want them to do.

    main.cpp
    Code:
    #include "player_class.cpp"
    #include <allegro.h>
    
    int main(){
      allegro_init();
      return 0;}
    END_OF_MAIN();
    player_class.cpp
    Code:
    #include "player_stats.hpp"
    
    int class_setup(int player_class){
      player_class = 1;
      return player_class;}
    
    player_class = class_setup(player_class);
    player_stats.hpp
    Code:
    int player_class = 0;
    That's the jist of what I want, but I get errors when compiling it. I'm just wondering why that is and how to fix it?
    Last edited by FoFGhost; 06-21-2011 at 09:40 PM.

  2. #2
    C++ Witch laserlight's Avatar
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    What are the error messages?

    Why is player_class is a global variable?

    Why do you include a source file in another source file?
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  3. #3
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    Yeah, you're doing a large number of things wrong. Here's the right way to do it:

    Code:
    //main.cpp
    #include "player.h"
    #include <allegro.h>
    #include <iostream>
    
    int main()
    {
      allegro_init();
      Player protagonist(1); //the main player 
      protagonist.setClass(2);//change the class
      protagonist.getClass(); //access the class
      return 0;
    }
    END_OF_MAIN();
    Code:
    //player.cpp
    #include "player.h"
    
    Player::Player(int pClass): pClass(pClass){
    }
    
    void Player::setClass(int pClass){
        this->pClass = pClass;
    }
    int Player::getClass() const{
      return pClass;
    }
    Code:
    //player.h
    #ifndef PLAYER_H
    #define PLAYER_H
    
    class Player{
      private:
        int pClass;
      public:
        Player(int pClass);
        void setClass(int pClass);
        int getClass() const;
    };
    
    #endif
    Better if you can understand this than jimmy your code to compile. I'm doing a lot of things differently, but each for a reason.
    It is too clear and so it is hard to see.
    A dunce once searched for fire with a lighted lantern.
    Had he known what fire was,
    He could have cooked his rice much sooner.

  4. #4
    Registered User FoFGhost's Avatar
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    Red face

    Quote Originally Posted by King Mir View Post
    Yeah, you're doing a large number of things wrong. Here's the right way to do it:

    Code:
    //main.cpp
    #include "player.h"
    #include <allegro.h>
    #include <iostream>
    
    int main()
    {
      allegro_init();
      Player protagonist(1); //the main player 
      protagonist.setClass(2);//change the class
      protagonist.getClass(); //access the class
      return 0;
    }
    END_OF_MAIN();
    Code:
    //player.cpp
    #include "player.h"
    
    Player::Player(int pClass): pClass(pClass){
    }
    
    void Player::setClass(int pClass){
        this->pClass = pClass;
    }
    int Player::getClass() const{
      return pClass;
    }
    Code:
    //player.h
    #ifndef PLAYER_H
    #define PLAYER_H
    
    class Player{
      private:
        int pClass;
      public:
        Player(int pClass);
        void setClass(int pClass);
        int getClass() const;
    };
    
    #endif
    Better if you can understand this than jimmy your code to compile. I'm doing a lot of things differently, but each for a reason.
    I think I get it now. We're setting things up in "classes" and that's why I'm getting weird errors with the constructors and deconstructurers.

    I have one more question. What's the point of ifndef?

    Thanks for the advice by the way! ;]

  5. #5
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    Quote Originally Posted by FoFGhost View Post
    I think I get it now. We're setting things up in "classes" and that's why I'm getting weird errors with the constructors and deconstructurers.

    I have one more question. What's the point of ifndef?

    Thanks for the advice by the way! ;]
    Glad it's clear, cause I was expecting to do a lot of explaining.

    The include gaurds as they are called make it so that you can include the same header file more than once in the same translation unit. Header files can #include classes that the depend on, and source file can include all the headers that they depend on. This can cause the same file to be included twice. Include gaurds prevent this from being a problem.
    It is too clear and so it is hard to see.
    A dunce once searched for fire with a lighted lantern.
    Had he known what fire was,
    He could have cooked his rice much sooner.

  6. #6
    Registered User FoFGhost's Avatar
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    Never mind! Fixed a simple typo! Ha ha.

    I forgot to include my header file in main instead of the .cpp file! ;D
    Last edited by FoFGhost; 06-21-2011 at 11:29 PM. Reason: Typo!

  7. #7
    Registered User FoFGhost's Avatar
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    I changed your code you gave me a little bit and it still runs great, for now. Lol.

    Code:
    //main.cpp
    #include "player_stats.hpp"
    #include <iostream>
    #include <allegro.h>
    
    int main(){
      allegro_init();
    
      Player protagonist;
      protagonist.setClass(0);
      
      Player player;
      player.setClass(1);
    
      std::cout << protagonist.getClass() << "\n\n";
      std::cout << player.getClass() << "\n\n";
      std::cin.get();
    
      return 0;}
    END_OF_MAIN();
    Code:
    //player_class.cpp
    #include "player_stats.hpp"
      
    void Player::setClass(int pClass){
      this -> pClass = pClass;}
    
    int Player::getClass() const{
      return pClass;}
    Code:
    //player_stats.hpp
    //#ifndef PLAYER_H
    //#define PLAYER_H
    
    class Player{
      private:
        int pClass;
      public:
        void setClass(int pClass);
        int getClass() const;};
    
    //#endif
    I commented those out so I can think more on taking them out. Tell me what you think though! ;]
    Last edited by FoFGhost; 06-21-2011 at 11:57 PM. Reason: Typo.

  8. #8
    C++まいる!Cをこわせ! Elysia's Avatar
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    Code:
    int Player::getClass() const{
      return pClass;}
    Don't do that. Many people would argue this is bad style.
    Put it on a new line instead.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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