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).
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.
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.
-1000000 9
-999,991
题目意思：A+B求和，然后每三位为一个单位加上一个“,”的格式输出。
解题思路：转换成字符串来遍历会很方便，注意若是负数第一位负号也要占位的，并且要求最后一位不能出现“,”，其实可以看看遍历到当前位时剩下的位数若是3的倍数，那么就需要加“,”了。
#include<iostream> #include<algorithm> #include<string> using namespace std; int main() { int a,b,len; int i; string str; cin>>a>>b; str=to_string(a+b); len=str.size(); for(i=0;i<len;i++) { cout<<str[i]; if(str[i]==‘-‘) { continue; } if((len-i-1)%3==0&&i!=len-1) { cout<<","; } } return 0; }
注意这里的to_string是C++11里面string中所包含的函数。
原文：https://www.cnblogs.com/wkfvawl/p/11017042.html