#include<stdio.h>
int sum(long num)  /*求一个十进制6位正整数各位数字之和*/
{
        long a = 0, b = 0, len;
        int sum = 0;
        for(len = 100000; len > 0; len = len / 10) {
                a = num / len;
                b = num % len;
                sum = sum + a;
                num = b;
        }
        return sum;
}

int main()
{
        int a;
        long num;
        scanf("%l", &num);
        printf("%d", sum(num));
}
问题是出在for语句块里面，但我不知道是什么问题，望高手能给我解答.

#include <stdio.h>

int main (void) {

        long int n;
        int i;
        int sum (long int n);
        scanf("%li",&n);
        printf("Result=%i\n",sum(n));
        return 0;

}

int sum (long int n) {
        int sum=0;
        do {
                sum+=n%10;
                n/=10;
        }while(n!=0);
        return sum;
}

#include<stdio.h>
int sum(long num)  /*求一个十进制6位正整数各位数字之和*/
{
        long a = 0, b = 0, len;
        int sum = 0;
        for(len = 100000; len > 0; len = len / 10) {
                a = num / len;
                b = num % len;
                sum = sum + a;
                num = b;
        }
        return sum;
}

int main()
{
        int a;
        long num;
        scanf("%ld", &num);//这里改下就好了
        printf("%d", sum(num));
}

算法不太好，而且不对，还是看看2楼的标准算法吧

[ 本帖最后由 shinan77 于 2011-5-9 12:54 编辑 ]

晕了，弄反了？没有吧！

2楼，能否解答下scanf("%li",&n);里的%li为什么能编译通过？书上怎么没有这个啊？