计算0～10的阶乘 使用递归

#include <stdio.h>
long factorial(long);

int main(){
    int i;
    for (i = 0; i <= 10; i++) {
        printf("%d!=%ld\n", i, factorial(i));
    }
}

long factorial(long a){
    if (a <= 1) {
        return 1;
    }
    else{
        return (a * factorial(a - 1));
    }
}