P51第7题

#include <stdio.h>
#include <conio.h>
int main()
{
 char a,b;
 while(1)
 {
  printf("请输入两个字符\n");
a=getche();
printf("\n");
b=getche();
printf("\n");
if(a<b)
{
 if((a-b)%2==0)
  printf("后继字符是%c\n",b+1);
 else
  printf("前驱字符是%c\n",a-1);
}
else if(a>b)
{
 if((a-b)%2==0)
  printf("后继字符是%c\n",a+1);
 else
  printf("前驱字符是%c\n",b-1);
}
 }while(getchar()==!'\n');
 return 0;
}