[RESOLVED] Pointers in a Class

[richard_tominez]

it doesn't shows the correct values

/*Triangle.hpp*/
#include <iostream>
using namespace std;
class Triangle
{
  public:
    Triangle();
    ~Triangle();
    int GetSideC() const {return *itsSideC;}
    int GetSideA() const {return *itsSideA;}
    int GetSideB() const {return *itsSideB;}
    void SetSideC(int c) {itsSideC = &c;}
    void SetSideA(int a) {itsSideA = &a;}
    void SetSideB(int b) {itsSideB = &b;}
  private:
    int *itsSideC;
    int *itsSideA;
    int *itsSideB;
};

Triangle::Triangle()
{
  itsSideC = new int (0);
  itsSideA = new int (0);
  itsSideB = new int (0);
}

Triangle::~Triangle()
{
  delete itsSideC;
  delete itsSideA;
  delete itsSideB;
}


/*myTriangle.cpp*/
#include "Triangle.hpp"

int main()
{
  Triangle myTriangle;
  myTriangle.SetSideC(5);
  myTriangle.SetSideA(4);
  myTriangle.SetSideB(3);
  
  cout << "Triangle" << endl;
  cout << "Side C:\t" << myTriangle.GetSideC() << endl;
  cout << "Side A:\t" << myTriangle.GetSideA() << endl;
  cout << "Side B:\t" << myTriangle.GetSideB() << endl;
  
  cin.get();
  return 0;
}

[laasunde]

Why are you using int pointers in the first place, why not just an int ?

I believe the problem is that 'int a' is passed-by-copy, so when you do '&a', its a temp pointer you are using to store inside the class.

myTriangle.SetSideA(4);
void SetSideA(int a) {itsSideA = &a;}

Would advice you to change to

int itsSideA;

or atleast do

void SetSideA(int a) {*itsSideA = a;}

[richard_tominez]

i used pointers because i'm studying in how to use them, anyway, thanks for the help!

[Paul McKenzie]

i used pointers because i'm studying in how to use them, anyway, thanks for the help!

You don't study something by using it in ways that no programmer will use them.

And BTW, this program using your class has memory leaks and double deletion errors:

int main()
{
   Triangle myTriangle;
   myTriangle.SetSideC(5);
   myTriangle.SetSideA(4);
   myTriangle.SetSideB(3);

   // add these three lines
   Triangle tri2 = myTriangle;
   Triangle tri3;
   tri3 = myTriangle;
}

This code creates a memory leak, and possibly crashes your program on exit. Now to fix this, you will see why it would have been better to just use int instead of int pointers.

Regards,

Paul McKenzie