recursive in c

#include <stdio.h>
int sum(int n);

int main() {
    int number, result;

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

    result = sum(number);

    printf("sum = %d", result);
    return 0;
}

int sum(int n) {
    if (n != 0)
        // sum() function calls itself
        return n + sum(n-1); 
    else
        return n;
}

/*
Program: Factorial of a given number using recursive function.
Author: Codesansar
Date: Jan 22, 2018
*/
#include<stdio.h>
#include<conio.h>

int fact(int n); /* Function Definition */

void main()
{
 int num, res;
 clrscr();
 printf("Enter positive integer: ");
 scanf("%d",&num);
 res = fact(num); /* Normal Function Call */
 printf("%d! = %d" ,num ,res);
 getch();
}
int fact(int n) /* Function Definition */
{
 int f=1;
 if(n <= 0)
 {
  return(1);
 }
 else
 {
  f = n * fact(n-1); /* Recursive Function Call as fact() calls itself */
  return(f);
 }
}