C Primer Plus7-5

/*5．（用switch）编写一个程序。该程序读取整数，直到输入 0。输入终止后，程序应该报告输入的偶数（不包括0）总个数、偶数的平均值，输入的奇数总个数以及奇数的平均值。*/

#include<stdio.h>
#include<stdlib.h>

int main()
 {
     int a, odd = 0, even = 0;
     int even_sum = 0, odd_sum = 0;

     printf("Please input numbers:");

     while (1)
      {

          scanf("%d", &a);

          if (a == 0)
              break;

          switch (a % 2)
           {
               case 0: even++;
                       even_sum += a;
                       break;      

               case 1: odd++;
                       odd_sum += a;
                       break;
           }
      }

     if (odd == 0 && even == 0)
         printf("0evens  even's average is 0     0odds  odd's average is 0\n");
     else
         printf("%devens  even's average is %d     %dodds  odd's average is %d\n", even, even_sum / even, odd, odd_sum / odd);

     system("pause");
     return 0;
}