Access an object from another file.

[cbarmpar]

Hi all,

I am new to Linux and c++ programming.

What I am trying to do is to declare an object in a .cpp and be able to access it from main.At the moment my code creates a new object in the ena.cpp and cannot use the one from the alpha.cpp. How can i access the object from alpha.cpp (bita.dio=6) from the main (ena.cpp).

Many thanks in advance.

ena.cpp

#include <iostream>
#include "alpha.h"
#include "bita.h"  
using namespace std;
 
int main() 
{
  A ob(4);
  B bita;//<this creates a new project which is irrelevant of the one i need to pass from alpha.cpp
  			// i need to remove that
  cout << ob.get_a();
  cout << bita.dio;//<-- This currently outputs 2 (and not 6 as i want)
    //cout << par;
  return 0;
}

#include <iostream>
#include "alpha.h"
#include "bita.h"  
using namespace std;

int main() 
{
  A ob(4);
  B bita;//<this creates a new project which is irrelevant of the one i need to pass from alpha.cpp
  			// i need to remove that
  cout << ob.get_a();
  cout << bita.dio;//<-- This currently outputs 2 (and not 6 as i want)
    //cout << par;
  return 0;
}

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alpha.cpp

#include "alpha.h"
#include "bita.h"
A::A(int x)
{ 
	B bita; 
    a = bita.ena;
   bita.dio = 6;//<---------- i want this to be accesible by ena.cpp directly
}
 
int A::get_a()
{
  return a;
}

#include "alpha.h"
#include "bita.h"
A::A(int x)
{ 
	B bita; 
    a = bita.ena;
   bita.dio = 6;//<---------- i want this to be accesible by ena.cpp directly
}

int A::get_a()
{
  return a;
}

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alpha.h

#include "bita.h"
#ifndef ALPHA_H
#define ALPHA_H
 
class A {
  int a;
public:
  A(int x);
  int get_a();
};
 
#endif /*ALPHA_H_*/

#include "bita.h"
#ifndef ALPHA_H
#define ALPHA_H

class A {
  int a;
public:
  A(int x);
  int get_a();
};

#endif /*ALPHA_H_*/

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bita.h

#include "bita.h"
#ifndef ALPHA_H
#define ALPHA_H
 
class A {
  int a;
public:
  A(int x);
  int get_a();
};
 
#endif /*ALPHA_H_*/

#include "bita.h"
#ifndef ALPHA_H
#define ALPHA_H

class A {
  int a;
public:
  A(int x);
  int get_a();
};

#endif /*ALPHA_H_*/

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bita.cpp

#include "bita.h"
 
B::B(){
	ena = 1;
	dio = 2;
	tria = 3;
}

#include "bita.h"

B::B(){
	ena = 1;
	dio = 2;
	tria = 3;
}

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[danadam]

How can i access the object from alpha.cpp (bita.dio=6) from the main (ena.cpp).

alpha.cpp

#include "alpha.h"
#include "bita.h"
A::A(int x)
{ 
	B bita; 
    a = bita.ena;
   bita.dio = 6;//<---------- i want this to be accesible by ena.cpp directly
}

#include "alpha.h"
#include "bita.h"
A::A(int x)
{ 
	B bita; 
    a = bita.ena;
   bita.dio = 6;//<---------- i want this to be accesible by ena.cpp directly
}

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You cannot because 'bita' is created locally in 'A' constructor. When 'A' constructor finishes it's job then 'bita' is destroyed. You can add your own destructor to 'B' which will print something and see yourself.

You have to made 'bita' a member of 'A' class:

class A {
  B bita;
  int a;
public:
  A(int x);
  int get_a();
  B * get_bita();
};
 
A::A(int x) {
  bita.dio = 6;
}
 
B * A::get_bita() {
  return &bita;
}
 
int main() {
  A ob(4);
  cout << ob.get_bita()->dio;   // will print 6
}

class A {
  B bita;
  int a;
public:
  A(int x);
  int get_a();
  B * get_bita();
};

A::A(int x) {
  bita.dio = 6;
}

B * A::get_bita() {
  return &bita;
}

int main() {
  A ob(4);
  cout << ob.get_bita()->dio;   // will print 6
}

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