More on Class & Object: Constructor in C++

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Program Reference: Cpp_Programs/ Day_03/ Prog_01.cpp

#include<stdlib.h> 
#include <iostream> 
class A
{
  private:
    int a, b, c;

  public:

    A(void){std::cout<<"\nThis is Default(!) Constructor of class A Running....";}

    A(int x){ std::cout<<"\nThis is Constructor1 of class A Running....\n"; a=x;}

    A(int x, int y){std::cout<<"\nThis is Constructor2 of class A Running....\n"; a=x; b=y;}

    A(int x, int y, int z){
      std::cout<<"\nThis is Constructor3 of class A Running....\n"; a=x; b=y; c=z;}

    A( A &ob){std::cout<<"\nCopy Constructor Running....\n"; a=ob.a; b=ob.b; c=ob.c;}

    ~A(void){std::cout<<"\nThis is Default Destructor of class A Running....\n";}

    void Display(void) {std::cout<<"\nA = "<<a<<"\tB = "<<b<<"\tC = "<<c<<"\n\n";}
};

int main(void)
{
  system("clear");  //TO CLEAR THE SCREEN [use clrscr(); in windows]
  std::cout<<"\n\t\t\tDemonstration of Constructor-Destructor: Implicit Call\n";

  A ob1;

  std:: cout<<"\nEnd of the Program....\n\n\n";
}

Output

$ g++ Prog_01.cpp
$ ./a.out

            Demonstration of Constructor-Destructor: Implicit Call

This is Default(!) Constructor of class A Running....
End of the Program....



This is Default Destructor of class A Running....
$

Program Reference: Cpp_Programs/ Day_03/ Prog_02.cpp

#include "A.class"
#include<stdlib.h> 
#include <iostream> 

int main(void)
{
  system("clear");  //TO CLEAR THE SCREEN [use clrscr(); in windows]
  std::cout<<"\n\t\t\tDemonstration of Constructor-Destructor: Implicit Call\n";

  A ob1;
  ob1.Display();

  std:: cout<<"\n\nEnd of the Program....\n\n\n";
}

Output

$ g++ Prog_02.cpp
$ ./a.out

            Demonstration of Constructor-Destructor: Implicit Call

This is Default(!) Constructor of class A Running....
A = -1217167360    B = 134514923    C = -1218494464



End of the Program....



This is Default Destructor of class A Running....
$

Program Reference: Cpp_Programs/ Day_03/ Prog_03.cpp

#include "A.class"
#include<stdlib.h> 
#include <iostream> 
int main(void)
{
  system("clear");  //TO CLEAR THE SCREEN [use clrscr(); in windows]
  std::cout<<"\n\t\t\tDemonstration of Constructor-Destructor: Explicit Call\n";

  A ob1;
  ob1.Display();

  A ob2(10);
  ob1.Display();
  ob2.Display();
}
 

Output

$ g++ Prog_03.cpp
$ ./a.out

            Demonstration of Constructor-Destructor: Explicit Call

This is Default(!) Constructor of class A Running....
A = -1076302324    B = -1219926867    C = -1218378812


This is Constructor1 of class A Running....

A = -1076302324    B = -1219926867    C = -1218378812


A = 10    B = 134515019    C = -1218379776


This is Default Destructor of class A Running....

This is Default Destructor of class A Running....
$

Program Reference: Cpp_Programs/ Day_03/ Prog_04.cpp

#include "A.class"
#include<stdlib.h> 
#include <iostream> 

int main(void)
{
  system("clear");  //TO CLEAR THE SCREEN [use clrscr(); in windows]
  std::cout<<"\n\t\t\tDemonstration of Constructor-Destructor: Implicit Call\n";

  A ob1(10);
  ob1.Display();

  ob1 = A(123);
  ob1.Display();

  ob1 = A(11, 22);
  ob1.Display();

  ob1 = A(1, 2, 3);
  ob1.Display();
}

Output

$ g++ Prog_04.cpp
$ ./a.out

            Demonstration of Constructor-Destructor: Implicit Call

This is Constructor1 of class A Running....

A = 10    B = -1217444392    C = 1


This is Constructor1 of class A Running....

This is Default Destructor of class A Running....

A = 123    B = 1    C = -1080157100


This is Constructor2 of class A Running....

This is Default Destructor of class A Running....

A = 11    B = 22    C = -1218526268


This is Constructor3 of class A Running....

This is Default Destructor of class A Running....

A = 1    B = 2    C = 3


This is Default Destructor of class A Running....
$

Program Reference: Cpp_Programs/ Day_03/ Prog_05.cpp

#include "A.class"
#include<stdlib.h> 
#include <iostream> 

int main(void)
{
  system("clear");  //TO CLEAR THE SCREEN [use clrscr(); in windows]
  std::cout<<"\n\t\t\tDemonstration of Copy Constructor\n";

  A ob1(10, 2, 3);
  ob1.Display();
  
  A ob2(ob1); 
  ob1.Display();
  ob2.Display();
}

 

Output

$ g++ Prog_05.cpp
$ ./a.out

            Demonstration of Copy Constructor

This is Constructor3 of class A Running....

A = 10    B = 2    C = 3


Copy Constructor Running....

A = 10    B = 2    C = 3


A = 10    B = 2    C = 3


This is Default Destructor of class A Running....

This is Default Destructor of class A Running....
$

Program Reference: Cpp_Programs/ Day_03/ Prog_06.cpp

#include "A.class"
#include<stdlib.h>
#include <iostream>

int main(void)
{
  int a,b,c;

  system("clear");  //TO CLEAR THE SCREEN [use clrscr(); in windows]
  std::cout<<"\n\t\t\tDemonstration of Copy Constructor\n";

  std::cout<<"Please Enter Three Values";
  std::cin>>a>>b>>c;

  A ob1(a,b,c);
  ob1.Display();
 
  A ob2(ob1);
  ob1.Display();
  ob2.Display();
}

Output

$ g++ Prog_06.cpp
$ ./a.out
            Demonstration of Copy Constructor
Please Enter Three Values1
2
3

This is Constructor3 of class A Running....

A = 1    B = 2    C = 3


Copy Constructor Running....

A = 1    B = 2    C = 3


A = 1    B = 2    C = 3


This is Default Destructor of class A Running....

This is Default Destructor of class A Running....
$

Content of A.Class

#include <iostream>
class A
{
  private:
    int a, b, c;

  public:

    A(void){std::cout<<"\nThis is Default(!) Constructor of class A Running....";}

    A(int x){ std::cout<<"\nThis is Constructor1 of class A Running....\n"; a=x;}

    A(int x, int y){std::cout<<"\nThis is Constructor2 of class A Running....\n"; a=x; b=y;}

    A(int x, int y, int z){
      std::cout<<"\nThis is Constructor3 of class A Running....\n"; a=x; b=y; c=z;}

    A( A &ob){std::cout<<"\nCopy Constructor Running....\n"; a=ob.a; b=ob.b; c=ob.c;}

    ~A(void){std::cout<<"\nThis is Default Destructor of class A Running....\n";}

    void Display(void) {std::cout<<"\nA = "<<a<<"\tB = "<<b<<"\tC = "<<c<<"\n\n";}
};