PAT_1001

1001. A+B Format (20)

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

Each input file contains one test case. Each case contains a pair of integers a and b where -1000000 <= a, b <= 1000000. The numbers are separated by a space.

Output

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

-999,99
1

题目的难点在于按照标准格式从尾开始每三位小数加一个逗号输出。

此时我选择的解决方法是把整数转换成字符串   to_string()

再判断字符串的第一个字符是否是‘-’号，如果是的话防止在符号和数字之间加上错误的‘，’。

代码如下：

#include <iostream>
#include <string>
using namespace std;

int main()
{
    int a,b;
    int ans=0;
    //c;
    cin>>a>>b;
    string str;
    str=to_string(a+b); //转为字符串
    int len = str.length();
    char c=str[0];
    //cout<<c<<endl;
    if(c=='-')
        ans=1;
    //cout<<len<<endl;
    for(int i=len-3; i > ans; i -= 3)
        str.insert(i, ",");//插入逗号。
    cout<<str<<endl;//输出结果。
    return 0;
}