C++ Recursion

Recursion is a powerful concept in programming that involves calling a function from within itself. In C++, recursion can be used to solve problems that are naturally recursive in nature, such as factorial calculation, Fibonacci series, and tree traversal.

A recursive function must have a base case, also known as the stopping condition, which terminates the recursion. If the base case is not met, the function calls itself with a modified set of inputs until the base case is met and the recursion terminates.

Example: Factorial Calculation

1#include <iostream>
2using namespace std;
3 
4int factorial(int num)
5{
6    if (num == 0)
7        return 1;
8 
9    return num * factorial(num - 1);
10}
11 
12int main()
13{
14    int num;
15 
16    cout << "Enter a positive integer: ";
17    cin >> num;
18 
19    cout << "Factorial of " << num << " is " << factorial(num) << endl;
20 
21    return 0;
22}

Output:

1Enter a positive integer: 5
2Factorial of 5 is 120

It is important to note that recursion can have a large impact on the performance of your code, as each recursive call results in the creation of a new stack frame. Therefore, it is essential to use recursion carefully and make sure that the base case is well defined and will always be reached.