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Sarvech Qadir

The **factorial** of a number `n`

, represented by `n!`

, is a product of `n`

with all the positive numbers less than or equal to `n`

. For example, $factorial(5) =
5 * 4 * 3 * 2 * 1 = 120$

Let’s see how we can find factorial in C. There are two methods:

- Using a loop
- Using recursion

Let’s explore both of them.

#include <stdio.h> int main() { int n, i; // since we are taking, set the start value at 1. int factorial = 1; // define the value of n for which we have // to compute the factorial. n = 5; // run the loop from 1 to that number, multiplying // the previous result with i. // no factorial for negative number, check if number is negative if(n<0) { printf("Factorial does not exist"); return 1; } for (i = 1; i <= n; ++i) { factorial = factorial * i; } printf("Factorial of %d = %d", n, factorial); return 0; }

#include <stdio.h> int factorial(int n) { // base case. if (n <= 1) return 1; // recursive case. return n * factorial(n-1); } int main() { int n; // define the value of our n for which we have // to compute the factorial. n = -5; if(n<0) { printf("factorial does not exist"); return 1; } // call the factorial(n) function. printf("Factorial of %d = %d", n, factorial(n)); return 0; }

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c

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Sarvech Qadir

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