【C语言】PAT甲级训练题目 1001题总结

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链接：原题

原题内容：

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 Specification:
Each input file contains one test case. Each case contains a pair of integers a and b where -10​≤a,b≤10​​​. 

The numbers are separated by a space.

Output Specification:
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

答案：

#include 
#include 

int main()
{
    int i,j,a,b,sum,num1,num2;
    int num[8];
    i=0;
    scanf("%d%d",&a,&b);
    sum=a+b;
    if(sum<0)
        printf("-"); 
    if(sum==0){
      printf("0");
      exit(0);   //special
    }
    while(sum)
    {
        num[i]=abs(sum%10);
        i++;
        sum/=10;
    }
    for (j=i-1;j>=0;j--)
    {
        printf("%d",num[j]);
        if(j%3==0 && j!=0)
            printf(",");
    }
    return 0;
}