PAT 1001 Format

problem

1001 A+B Format (20)（20 point(s)）
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
-999,991

anwser

#include <iostream>
int main(){
	int a, b;
	int c;
	int end[10];
	std::cin>>a>>b;
	c = a+b;
	if (c==0) {
		std::cout<<"0";
		return 0;
	}
	if (c<0) {
		std::cout<<"-";
		c = -c;
	}
	int index = 0;
	while(c>0){
		end[index++] = c%1000;
		c/=1000;
	}
  	for(int i = index - 1; i >= 0; i--){
	  	if(i != index-1){
		  	if(end[i] == 0)
		  		std::cout<<"000";
		    if(end[i] > 99)
		    	std::cout<<end[i];
		    else if(end[i] > 9){
		    	std::cout<<"0";
		    	std::cout<<end[i];
		    }
		    else if (end[i] > 0){
		    	std::cout<<"00";
		    	std::cout<<end[i];
			}
		}
		else
			std::cout<<end[i];
	    if (i != 0)
	      std::cout<<",";
	}
	return 0;
}

experience

• 边界条件要注意的
  • c ==0
• 除首个数字外 end[i] == 0 的情况，并且要分类讨论
• 首个数字不需要特殊处理