factorial using recursion in c

1#include<stdio.h>
2fact(int i, int k){
3    k=k*i;
4    i--;
5    if(i==0){
6        return k;
7    }
8    else{
9        fact(i, k);
10    }
11}
12int main()
13{
14    int k = 1, i, factorial;
15    scanf("%d",&i);
16    factorial = fact(i, k);
17    printf("%d\n",factorial);
18    return 0;
19}

1#include <stdio.h>
2
3unsigned long long int factorial(unsigned int i) 
4{
5if(i <= 1) 
6{
7  return 1;
8}
9   return i * factorial(i - 1);
10}
11
12int  main() {
13   int i = 12;
14   printf("Factorial of %d is %d\n", i, factorial(i));
15   return 0;
16}

1#include <stdio.h>
2
3unsigned long long int factorial(unsigned int i) {
4
5   if(i <= 1) {
6      return 1;
7   }
8   return i * factorial(i - 1);
9}
10
11int  main() {
12   int i = 12;
13   printf("Factorial of %d is %d\n", i, factorial(i));
14   return 0;
15}