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Basic
Switch Case
Goto
Operators
if Statement
Nested if
While Loop
For Loop
Patterns
Array
2D Array
String Function Example
Pointers
Recursion Function
Structure
Excersises
Others



C Program to Find Factorial of a Number Using Recursion


Write a C program to find factorial of a number using recursion

  • Prompt and read an integer input from the user.
  • Check if the number is negative and handle it with an error message.
  • Call the recursion factorial() function to compute the factorial for valid input.
  • Base case returns 1 for 0 or 1, and the recursion case multiplies n by factorial(n-1).
Example : pgm.c 
#include <stdio.h>

// Recursion function to calculate factorial
int factorial(int n) {
    if (n == 0 || n == 1)  // Base case
        return 1;
    else
        return n * factorial(n - 1);  // Recursion call
}

int main() {
    int num;

    printf("Enter a number: ");
    scanf("%d", &num);

    if (num < 0)
        printf("Factorial is not defined for negative numbers.\n");
    else
        printf("Factorial of %d is %d\n", num, factorial(num));

    return 0;
}

Output :

Enter a number: 5
Factorial of 5 is 120