Lecture 22:- Functions & some Problem Statement

Functions are reusable blocks of code that perform a specific task. They help in modularizing the code and make it more organized and easier to maintain. A function is defined with a return type (if applicable), a function name, and optional parameters. Let's explore functions and a problem statement:

Functions:

Syntax of a simple function in C++:

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return_type function_name(parameters) {    // Function body    // Code to perform a specific task    // Optionally, return a value }

Example of a function that adds two integers and returns their sum:

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#include <iostream> int add(int a, int b) {    int sum = a + b;    return sum; } int main() {    int num1 = 5, num2 = 10;    int result = add(num1, num2);    std::cout << "Sum: " << result << std::endl;    return 0; }

Problem Statement:

Let's consider a simple problem statement: Write a C++ function to calculate the factorial of a non-negative integer.

Factorial Function: The factorial of a non-negative integer n, denoted as n!, is the product of all positive integers less than or equal to n.

Example: Factorial of 5 (5!) is 5 * 4 * 3 * 2 * 1 = 120.

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#include <iostream> // Function to calculate the factorial int factorial(int n) {    if (n == 0 || n == 1) {        return 1;    } else {        return n * factorial(n - 1);    } } int main() {    int num = 5;    int result = factorial(num);    std::cout << "Factorial of " << num << " is: " << result << std::endl;    return 0; }

In the above example, we have defined a recursive function factorial that calculates the factorial of the input number n. The function checks for the base case (n == 0 or n == 1) and returns 1. Otherwise, it recursively calls itself with n - 1 until it reaches the base case.

Feel free to experiment with different inputs for the factorial function and see how it calculates the factorial of the given number using recursion.