C Primer Plus7-6

/*6．编写一个程序读取输入，直到#，并报告序列 ei 出现的次数。
此程序必须要记住前一个字符和当前的字符。用诸如“Receive your eieio award.”的输入测试它。*/

#include<stdio.h>
#include<stdlib.h>
#define STOP '#'
int main()
 {
     char former = 0, present;
     int i = 0;

     printf("Please input:");

     while ((present = getchar()) != STOP)
      {
          if ((former == 'e') && (present == 'i'))
           {
               i++;
           }
               former = present;
        }

     printf("%dtimes\n", i);

     system("pause");
     return 0;
 }