【PAT】1001. A+B Format

#include<iostream>
#include<cmath>
using namespace std;
int main(){
    int a,b;
    while(cin>>a>>b)
    {
        int c=fabs(a+b);
    int cnt=0;
    int aa=1;
    char str[10];
    while(c){
        char t=c%10+'0';
        str[cnt++]=t;
        if(aa%3==0 &&c/10!=0) str[cnt++]=',';
        aa++;
        c/=10;
    }
    if(a+b<0) cout<<"-";
    if(a+b==0) cout<<"0";
    for(int i=cnt-1;i>=0;i--){
        cout<<str[i];
    }
    cout<<endl;
    }


    return 0;
}

注意当结果为0的情况

下面是简洁代码

#include<stdio.h>
int main()
{
  int a,b;
  int sum;
  while(scanf("%d%d\n",&a,&b) != EOF){
        sum = a+b;
	if(sum < 0){
	printf("-");
	sum = -sum;
	}
    if(sum>=1000000){
        printf("%d,%03d,%03d\n",sum/1000000, (sum/1000)%1000, sum%1000);
    }
    else if(sum >= 1000){
        printf("%d,%03d\n",sum/1000,sum%1000);
    } else{
        printf("%d\n", sum);
    }
  }
  return 0;
}