PAT甲级 1001 A+B Format

题目链接：https://pintia.cn/problem-sets/994805342720868352/problems/994805528788582400

1001 A+B Format （20 分）

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​6​​≤a,b≤10​6​​. 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

AC代码：

#include <iostream>
#include<cstdio>
using namespace std;
int main(int argc, char const *argv[])
{
    int a, b;
    cin >> a >> b;

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

    } else if (c >= 1000) {
        printf("%d,%03d\n", c / 1000, c % 1000);
    } else {
        printf("%d\n", c );
    }

    return 0;
}