C++ Recursion: Calculating factorial using recursive function

Last update on April 14 2025 12:47:12 (UTC/GMT +8 hours)

2. Factorial Using Recursion

Write a C++ program to calculate the factorial of a given number using recursion.

Sample Solution:

C Code:

#include <iostream> // Including the Input/Output Stream Library

// Recursive function to calculate the factorial
int factorial(int n) {
  // Factorial of 0 or 1 is 1
  if (n == 0 || n == 1)
    return 1;

  // Recursive case: factorial of n is n multiplied by factorial of (n-1)
  return n * factorial(n - 1);
}

int main() {
  int num;
  std::cout << "Input a number: "; // Prompting the user to input a number
  std::cin >> num; // Reading the input number from the user

  // Calculate the factorial using recursion
  int fact = factorial(num); // Calling the recursive function to calculate factorial

  std::cout << "Factorial of " << num << " is: " << fact << std::endl; // Displaying the factorial

  return 0; // Returning 0 to indicate successful execution of the program
}

Sample Output:

Input a number: 3
Factorial of 3 is: 6

Input a number: 10
Factorial of 10 is: 3628800

Explanation:

In the above exercise

• The "factorial()" function takes an integer n as a parameter and calculates the factorial of n using recursion.
• The base case is when n is 0 or 1, in which case the function returns 1.
• In the recursive case, the function returns n multiplied by n-1's factorial.
• The main function accepts a number from the user, calculates the factorial using the factorial function, and displays the result.

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C++ program to calculate the factorial of a number recursively and use memoization to optimize repeated calls.
• Write a C++ program that implements a tail-recursive factorial function to minimize stack usage.
• Write a C++ program to compute factorial recursively and print the intermediate multiplication steps for clarity.
• Write a C++ program to compute factorial using recursion while handling large input values with proper error checking.

CPP Code Editor:

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Next C++ Exercise: Implementing recursive function for fibonacci numbers.