PAT (Advanced Level) Practice A1001 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 −. 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

题型：字符串处理

思路：

判断打印","的条件，当(i + 1) % 3 == len % 3 && i != len - 1时打印","

代码实现：

#include <iostream>
#include<string>
using namespace std;
int main() {
    int a, b;
    cin >> a >> b;
    string s = to_string(a + b);
    int len = s.length();
    for (int i = 0; i < len; i++) {
        cout << s[i];
        if (s[i] == '-') {
            continue;
        }
        if ((i + 1) % 3 == len % 3 && i != len - 1) {    //判断打印，的条件
            cout << ",";
        }
    }
    return 0;
}