pat1001 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 −. 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 题目分析：题目要求计算a+b的和并从右往左每三位加一个","正序输出，大致思路为将计算的数转换为字符后，然后一位一位输出，同时判断何时该加“,”。             难点在于这个地方，存在以下两种情况：1、若整个a+b和的位数是3的倍数，则重点考虑如何判断最后一位之后不加“,”如“324,113”不能为“324,113,”。                                                  2、若整个a+b和的位数不是3的倍数，则重点考虑如何实现从右往左每三位加一个“,”。

关键代码：

1 (i+1)%3==strlen(s)%3&&i!=strlen(s)-1  //s为数字转换后的字符数组

完整代码：

1 #include
        
          2 #include
         
           3 int main() 4 { 5     int a,b,i; 6     char s[10]; 7     scanf("%d %d",&a,&b); 8     sprintf(s, "%d", a+b);    //将数字转换为字符数组 9     for(i=0;i