[PAT甲级]1001 A+B Format （20 分)

题目

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

分析

水题，转换成字符串输出，考虑临界值为0的情况即可！

代码

#include<iostream>

#include<cmath>

#include<string>

using namespace std;

int main(){

    int a,b;

    cin>>a>>b;

    int x=a+b;

    if(x==0){

        cout<<0<<endl;

        return 0;

    }

    int flag=0,i=1;

    string str="";

    if(x<0) flag=1;

    x = abs(x);

    while (x>0) {

        str = char(x%10+'0') + str ;

        if(i%3==0 && x>=10)

            str = ',' + str ;

        x=x/10;

        i++;

    }

    if(flag==1) str='-'+str;

    cout<<str<<endl;

}