对在终端输入的单个字符进行分类

#include <stdio.h>

int main (void)
{
    char c;
    printf (Enter a single character:\n);
    scanf (%c, &c);

    if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
        printf (It's an alphabetic character.\n);
    else if (c >= '0' && c <= '9')
        printf (It's a digit.\n);
    else
        printf (It's a special character.\n);

    return 0;
}