例2-9

#include<stdio.h>
int main(void)
{
    int i,n;
    double product;

    printf("Enter n:");
    scanf_s("%d",&n);
    product=1;
    for(i=1;i<=n;i++){
        product=product*i;
    }
    printf("product=%.0f
",product);

    return 0;
}