程序代码：

#include <stdio.h>
int main(void)
{

 char c;

 switch(c=getchar())

 {case ('0'<=c && c<='9')  : printf("this is a digit\n");             break;
  case ('a'<=c && c<='z')  : printf("this is a small letter\n");    break;
  case ('A'<=c && c<='Z')  : printf("this is a capital letter\n");    break;
  default : printf("this is the other\n");

 }

 }--------------------Configuration: stu - Win32 Debug--------------------
Compiling...
c.c
E:\软件\VC6\MyProjects\stu\c.c(6) : error C2051: case expression not constant
E:\软件\VC6\MyProjects\stu\c.c(7) : error C2051: case expression not constant
E:\软件\VC6\MyProjects\stu\c.c(8) : error C2051: case expression not constant
执行 cl.exe 时出错.

c.obj - 1 error(s), 0 warning(s)