How do you write a C program to calculate the factorial within recursive function?

Answer 1

// Iterative solution

unsigned long iterativeFactorial(const unsigned long n) {

unsigned long i, factorial = 1;

for(i = 1; i <= n; i++) {

factorial *= i;

}

return factorial;

}

// Recursive solution

unsigned long recursiveFactorial(const unsigned long n) {

if(n <= 1) {

return n;

}

return n * recursiveFactorial(n - 1);

}

// Sample calls

int main() {

unsigned long n;

printf("Enter a number to find its factorial: ");

scanf("%u",&n);

printf("Iterative factorial: %u\n", iterativeFactorial(n));

printf("Recursive factorial: %u\n", recursiveFactorial(n));

return 0;

}

Answer 2

#include <stdio.h>

long double fact (long double n) {

return (n == 1) ? 1 : n * fact(n-1);

}

void main()

{

int n;

printf("Enter a number:\n>");

scanf("%d",&n);

printf("%d! = %Lf\n", fact(n));

//long double can hold much bigger numbers than say, int or double.

}

Answer 3

Note: This fails at N=20 due to truncation error

#include <stdio.h>

#define FALSE (0)

#define TRUE (1)

}

/* Microsoft 64-bit recursive */

unsigned long long NFactLongLongRecursive (unsigned long long N) {

if (N < 2) return 1;

if (N == 2) return 2;

return N * NFactLongLongRecursive (N - 1);

/* Example main line */

int main (int argc, char *argv[]) {

int N;

if (argc < 2) {

fprintf (stderr, "Usage: factorial N\n");

return 1;

}

N = atoi (argv[1]);

printf ("Recursive: %u! = %I64u\n", N, NFactLongLongRecursive (N));

return 0;

}