In this C++ tutorial, you will learn how to write a recursion function with the help of example C++ programs.
C Recursion Function
A function is called a recursion function if a call is made to the same function from within the body of the function.
Examples
1 Factorial using Recursion
In the following example, we shall write recursion function instead of looping techniques, to find the factorial of a number.
C++ Program
#include <iostream> using namespace std; /* * Recursion function to calculate factorial of a number */ int factorial(int n) { if (n==0) { return 1; } else { return n * factorial(n - 1); } } int main() { cout << factorial(4) << "\n"; cout << factorial(5) << "\n"; cout << factorial(6) << "\n"; }
Output
24 120 720
Explanation
factorial(4) = 4 * factorial(3) \ factorial(3) = 3 * factorial(2) \ factorial(2) = 2 * factorial(1) \ factorial(1) = 1 * factorial(0) | (1)
2 Find sum of first N numbers using recursion technique
In this example, we shall find the find the sum of first N natural numbers using recursion function.
C++ Program
#include <iostream> using namespace std; /* * Recursion function to calculate * sum of first n natural numbers */ int sumOfN(int n) { if (n==1) { return 1; } else { return n + sumOfN(n - 1); } } int main() { cout << sumOfN(4) << "\n"; cout << sumOfN(6) << "\n"; }
Output
10 21
Conclusion
In this C++ Tutorial, we learned how to use recursion technique with functions in C++.