Define Constructor in Outside Class Example Program In C++

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On this page (8sections)

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,

Constructors and Destructors in C++ Classes

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

Learn the concept first, then study the code:

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