c语言用递归求和1+2+3+4+...+n

#include <stdio.h>

int sum(int n);

int main() {
int n;
printf("Enter a positive integer: ");
scanf("%d", &n);
printf("Sum of 1 to %d is %d\n", n, sum(n));
return 0;
}

int sum(int n) {
if (n == 1) { // base case
return 1;
} else {
return n + sum(n-1); // recursive case
}
}