PAT甲级——A1001A+BFormat

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

很简单，数字转字符串即可

 #define _CRT_SECURE_NO_WARNINGS

 #include <iostream>
 #include <vector>
 #include <sstream>
 #include <string>
 #include <stack>

 using namespace std;

 int main()
 {
     int a, b,sum;
     string str;
     scanf("%d %d", &a, &b);
     sum = a + b;
     stringstream ss;
     ss << sum;
     ss >> str;

     ///此处可以通过sum/1000，然后转为字符串
     stack<string>res;
     int k;
     string s;
     for (k = str.length(); k > ;k-=)
     {
         s.assign(str.begin() + k - , str.begin() + k);
         res.push(s);
         res.push(",");
     }
     s.assign(str.begin(), str.begin() + k);
     if (s == "-")
         res.pop();
     res.push(s);
     while (!res.empty())
     {
         cout << res.top();
         res.pop();
     }
     return ;
 }

更简洁点

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