要求出入1-4，其它的输入都是错误，重新输入。c代码如下，可是当输入错误时，总是显示2次"Invalid value entered. Must be 1 to 4, please re-enter:"。请大虾指教。我是在dev c++上运行。
#include<stdio.h>
#include<stdlib.h>
main()
{     int a=1; char k;
      printf("Enter Section Number:");
      while(a)
       {
         
            k=getchar();
            if     (k<'5'&&k>'0') a=0;
            else    printf("Invalid value entered. Must be 1 to 4, please re-enter:");
       }
printf("%c",k);
system("pause");
return 0;
}