Define Constructor in Outside Class Example Program In C++


Constructor Overview

Definition

A constructor is a special member function of the class which has the same name as that of the class. It is automatically invoked when we declare/create new objects of the class.

for better understanding about Constructor,

Constructor Syntax for Ouside Class

class class_name {
public:
   //Constructor declaration
   class_name();

   //... other Variables & Functions
}

// Constructor definition outside Class
class_name::class_name() {
   // Constructor code 
}

Simple Program Constructor Algorithm/Steps:

  • STEP 1:  Start the program.
  • STEP 2:  Declare the class as Example with a and b variables.
  • STEP 3:  Declare the 'Constructor declaration' in class
  • STEP 4:  Define 'Constructor definition' outside Class with a and b initialization
  • STEP 5:  Write function for display values a and b
  • STEP 6:  Main function declaration and defintion
  • STEP 7:  Create object for Example class in main Fucntion
  • STEP 8:  Call display function using Example class object.
  • STEP 9:  Check whether the k value is 1 or 0.
  • STEP 10: Stop the program.

Simple Constructor in Outside Class Declaration Example Program

/*  Simple Constructor in Outside Class Declaration Example Program In C++
    Understanding Class                             */

// Header Files
#include <iostream>
#include<conio.h>

using namespace std;

// Class Declaration

class Example {
   int a, b;
   //Access - Specifier
public:
   //Constructor declaration
   Example();

   //Member Functions for display 'a & b' Values.

   void Display() {
      cout << "Values :" << a << "\t" << b;
   }
};

// Constructor definition outside Class
Example::Example() {
   // Assign Values In Constructor
   a = 10;
   b = 20;
   cout << "Im Constructor : Outside Class\n";
}

int main() {
   cout << "Simple Constructor Outside Class Declaration Example Program In C++\n";

   // Object Creation For Class
   Example Object;
   // Constructor invoked.
   Object.Display();

   // Wait For Output Screen
   getch();
   return 0;
}

Sample Output

Simple Constructor Outside Class Declaration Example Program In C++
Im Constructor : Outside Class
Values :10      20