Programming Forums > Application Development > C++

cwl157 · Jul 11th, 2008, 8:38 PM

So i am making a c++ program with classes. I want to know how to use header files. I have some functions and some variables that are public. I know a head file has the class and the function declarations in it. I keep getting errors that the type is not right in the .h file. The class is called piece it has 4 public variables and 1 constructor. I say this:

class Piece;

to define the class and then i need to define the constructor too right? But i can't figure out how to do that and do i have to delare the variables. I couldn't find a good example of one on the internet so could someone give me a good example of a c++ header file for a class so i can see how i am supposed to write the declarations in it? Thanks.

Ancient Dragon · Jul 11th, 2008, 9:07 PM

There are lots of tutorials on the net. See these google links (click here)

lectricpharaoh · Jul 12th, 2008, 12:07 AM

Let's say your Piece class has one public constructor, and four methods to move it (left, right, up, and down). Your header file might look something like this:

 C++ Syntax (Toggle Plain Text) 
// piece.h
 public class piece
 {
   private:
     static int MAX_X;
      static int MAX_Y;
     int xPosition, yPosition;
   public:
     Piece(void);
     void moveLeft(void);
      void moveRight(void);
      void moveUp(void);
      void moveDown(void);
  };
// piece.h
 public class piece
 {
   private:
     static int MAX_X;
      static int MAX_Y;
     int xPosition, yPosition;
   public:
     Piece(void);
     void moveLeft(void);
      void moveRight(void);
      void moveUp(void);
      void moveDown(void);
  };

Your .cpp file might be like so:

 C++ Syntax (Toggle Plain Text) 
// piece.cpp
#include "piece.h"
int Piece :: MAX_X = 20;
 int Piece :: MAX_Y = 20;
 
Piece :: Piece(void)
 {
   xPosition = MAX_X / 2;
   yPosition = MAX_Y / 2;
   // other initialization code
 }
 
  void Piece :: moveLeft(void)
  {
    --xPosition;
    if(xPosition < 0)
      xPosition = 0;
  }
 
  void Piece :: moveRight(void)
  {
    ++xPosition;
    if(xPosition > MAX_X)
      xPosition = MAX_X;
  }
 
  void Piece :: moveUp(void)
  {
    --yPosition;
    if(yPosition < 0)
      yPosition = 0;
  }
 
  void Piece :: moveDown(void)
  {
    ++yPosition;
    if(yPosition < 0)
      yPosition = MAX_Y;
}
// piece.cpp
#include "piece.h"
int Piece :: MAX_X = 20;
 int Piece :: MAX_Y = 20;
 
Piece :: Piece(void)
 {
   xPosition = MAX_X / 2;
   yPosition = MAX_Y / 2;
   // other initialization code
 }
 
  void Piece :: moveLeft(void)
  {
    --xPosition;
    if(xPosition < 0)
      xPosition = 0;
  }
  
  void Piece :: moveRight(void)
  {
    ++xPosition;
    if(xPosition > MAX_X)
      xPosition = MAX_X;
  }
  
  void Piece :: moveUp(void)
  {
    --yPosition;
    if(yPosition < 0)
      yPosition = 0;
  }
  
  void Piece :: moveDown(void)
  {
    ++yPosition;
    if(yPosition < 0)
      yPosition = MAX_Y;
}

Basically, declarations go in the header file, and definitions go in the code file. Stuff like macros and inline functions go in the header, but (aside from inline functions) you should have no actual code in there.

cwl157 · Jul 12th, 2008, 2:35 PM

thanks lectricpharaoh thats exactly what i was looking for

Jabo · Jul 15th, 2008, 2:25 AM

Quote:

Originally Posted by xmo

nonsense

WOW what a bunch of gibberish
Nice try xmo; I don't know about anybody else, but I won't be following any of your links. No telling what could happen.

Not to mention 2 things about your post:
1. you tromped all over somebody else's thread
2. this has nothing to do with programming

Ancient Dragon · Jul 15th, 2008, 6:55 AM

Quote:

Originally Posted by Jabo

WOW what a bunch of gibberish
Nice try xmo; I don't know about anybody else, but I won't be following any of your links. No telling what could happen.

Not to mention 2 things about your post:
1. you tromped all over somebody else's thread
2. this has nothing to do with programming

I deleted it -- spam.

Jul 11th, 2008, 8:38 PM	#1
cwl157 Professional Programmer Join Date: Feb 2005 Posts: 345 Rep Power: 4	creating header files So i am making a c++ program with classes. I want to know how to use header files. I have some functions and some variables that are public. I know a head file has the class and the function declarations in it. I keep getting errors that the type is not right in the .h file. The class is called piece it has 4 public variables and 1 constructor. I say this: class Piece; to define the class and then i need to define the constructor too right? But i can't figure out how to do that and do i have to delare the variables. I couldn't find a good example of one on the internet so could someone give me a good example of a c++ header file for a class so i can see how i am supposed to write the declarations in it? Thanks.

Jul 11th, 2008, 9:07 PM	#2
Ancient Dragon PFO God In Training Join Date: Jun 2005 Location: near St Louis, MO. (USA) Posts: 598 Rep Power: 4	Re: creating header files There are lots of tutorials on the net. See these google links (click here) __________________ <<Freelance Programmer>> << Hobby Site>>

Jul 12th, 2008, 12:07 AM	#3
lectricpharaoh Caffeinated Neural Net Join Date: Jun 2005 Location: Wet west coast of Canada Posts: 1,120 Rep Power: 5	Re: creating header files Let's say your Piece class has one public constructor, and four methods to move it (left, right, up, and down). Your header file might look something like this: C++ Syntax (Toggle Plain Text) // piece.h public class piece { private: static int MAX_X; static int MAX_Y; int xPosition, yPosition; public: Piece(void); void moveLeft(void); void moveRight(void); void moveUp(void); void moveDown(void); }; // piece.h public class piece { private: static int MAX_X; static int MAX_Y; int xPosition, yPosition; public: Piece(void); void moveLeft(void); void moveRight(void); void moveUp(void); void moveDown(void); }; Your .cpp file might be like so: C++ Syntax (Toggle Plain Text) // piece.cpp #include "piece.h" int Piece :: MAX_X = 20; int Piece :: MAX_Y = 20; Piece :: Piece(void) { xPosition = MAX_X / 2; yPosition = MAX_Y / 2; // other initialization code } void Piece :: moveLeft(void) { --xPosition; if(xPosition < 0) xPosition = 0; } void Piece :: moveRight(void) { ++xPosition; if(xPosition > MAX_X) xPosition = MAX_X; } void Piece :: moveUp(void) { --yPosition; if(yPosition < 0) yPosition = 0; } void Piece :: moveDown(void) { ++yPosition; if(yPosition < 0) yPosition = MAX_Y; } // piece.cpp #include "piece.h" int Piece :: MAX_X = 20; int Piece :: MAX_Y = 20; Piece :: Piece(void) { xPosition = MAX_X / 2; yPosition = MAX_Y / 2; // other initialization code } void Piece :: moveLeft(void) { --xPosition; if(xPosition < 0) xPosition = 0; } void Piece :: moveRight(void) { ++xPosition; if(xPosition > MAX_X) xPosition = MAX_X; } void Piece :: moveUp(void) { --yPosition; if(yPosition < 0) yPosition = 0; } void Piece :: moveDown(void) { ++yPosition; if(yPosition < 0) yPosition = MAX_Y; } Basically, declarations go in the header file, and definitions go in the code file. Stuff like macros and inline functions go in the header, but (aside from inline functions) you should have no actual code in there. __________________ And once again, Probability proves itself willing to sneak into a back alley and service Drama as would a copper-piece harlot. - Vaarsuvius, Order of the Stick

Jul 12th, 2008, 2:35 PM	#4
cwl157 Professional Programmer Join Date: Feb 2005 Posts: 345 Rep Power: 4	Re: creating header files thanks lectricpharaoh thats exactly what i was looking for

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Programming Forums > Application Development > C++

creating header files