PAT-1001. A+B Format (20)

 Calculate a + b and output the sum in standard format -- that is, the digits must be separated into groups of three by commas (unless there are less than four digits).

    Input

    Each input file contains one test case. Each case contains a pair of integers a and b where -1000000 <= a, b <= 1000000. The numbers are separated by a space.

    Output

    For each test case, you should output the sum of a and b in one line. The sum must be written in the standard format.

    Sample Input

    -1000000 9

    Sample Output

    -999,991

宝宝表示讨厌英文，更讨厌了、考小学数学的英文；

总结：题意从开始到结束没有弄明白过，那个逗号怎么分后来百度才明白三位分级，，，，，然后思路不开阔，我竟然用字符串做有毛病！！！！主要是题意原因，还有数学确实不好，，，英语也不好，，，看清楚题意题意，a,b两个数之和的范围其实不大，直接做比较简单，宝宝献上宝宝觉得比较好的代码，代码是别人滴！

#include<stdio.h>
int main()
{
    int a,b;
    int sum;
    scanf("%d %d",&a,&b);


    sum = a+b;
    if(sum < 0)
    {
        printf("-");
        sum = -sum;
    }
    if(sum>=1000000)
    {
        printf("%d,%03d,%03d\n",sum/1000000, (sum/1000)%1000, sum%1000);
    }
    else if(sum >= 1000)
    {
        printf("%d,%03d\n",sum/1000,sum%1000);
    }
    else
    {
        printf("%d\n", sum);
    }


    return 0;
}

这个解法一般还算可以。我嫌代码长了点，，，宝宝走了，，，心累