其他的结果都是能实现，就是“This is a control character”个结果实现不了，怎么输入？
#include<stdio.h>
main()
{
  char c;
  printf("input a character: \n");
  c=getchar();
  if(c<32)
    printf("This is a control character\n"); //........
  else if(c>='0'&&c<='9')
       printf("This is a digit\n");
    else if(c>='A'&&c<='Z')
          printf("This is a capital letter\n");
          else if(c>='a'&&c<='z')
            printf("This si a small letter\n");
            else
            printf("This is an other character\n");

}

c=getchar();
  if(c<32)
    printf("This is a control character\n");
怎么实现这段程序的结果？？