Discuss default argument. Write a program to find perimeter of a square, rectangle and circle using function overloading.

 Default argument in C++ allows you to set default values for function parameters. If a value is not provided for a particular argument, then the default value will be used. This makes the function more flexible and easier to use.

Here is an example program that calculates the perimeter of a square, rectangle, and circle using function overloading and default arguments:

#include <iostream>

using namespace std;

const float pi = 3.14;

// Function to find perimeter of a square

float perimeter(float side = 1) {

    return 4 * side;

}

// Function to find perimeter of a rectangle

float perimeter(float length = 1, float width = 1) {

    return 2 * (length + width);

}

// Function to find perimeter of a circle

float perimeter(float radius = 1) {

    return 2 * pi * radius;

}

int main() {

    cout << "Perimeter of square with side 5 is: " << perimeter(5) << endl;

    cout << "Perimeter of rectangle with length 5 and width 3 is: " << perimeter(5, 3) << endl;

    cout << "Perimeter of circle with radius 4 is: " << perimeter(4) << endl;

    

    // Calling the functions with default arguments

    cout << "Perimeter of square with default side is: " << perimeter() << endl;

    cout << "Perimeter of rectangle with default length and width is: " << perimeter() << endl;

    cout << "Perimeter of circle with default radius is: " << perimeter() << endl;

    

    return 0;

}

In the program, we define three functions named perimeter() with the same name but different parameter lists. The first function finds the perimeter of a square, the second function finds the perimeter of a rectangle, and the third function finds the perimeter of a circle.

Each function has default arguments, which are used if no arguments are passed to the function. For example, if we call perimeter() with no arguments, the default argument of 1 will be used for the side parameter in the first function, the length and width parameters in the second function, and the radius parameter in the third function.

In the main() function, we call each of the perimeter() functions with different arguments and output the results. We also call the functions with no arguments, which will use the default arguments.

This program demonstrates how function overloading and default arguments can be used to create flexible and easy-to-use functions.