编程实现求一个三位数各个位之和

#include <stdio.h>
int main()
{
    int num;
    int gw,sw,bw,sum;
    scanf("%d",&num);
    gw=num%10;
    sw=num%100/10;
    bw=num/100;
    sum=gw+sw+bw;
    printf("%d",sum);
}

输入:321

输出结果为:6