俺是菜鸟，想问个问题
#include"stdio.h"

int main()
{
char c;
printf("input a character:");
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\n");
else if(c>='a'&&c<='z')
printf("this is a small\n");
else
printf("this is an other character\n");
}
为什么我输入21，结果是this is a digit 呢