//练习三
char c = ‘0‘;
scanf("%c",&c);
if ( c >= ‘0‘ && c <= ‘9‘) {
printf("this is digital");
}else if( c >= ‘A‘ && c <= ‘Z‘){
printf("this is capital letter");
}else if( c >= ‘a‘ && c <= ‘z‘){
printf("this is letter");
}else {
printf("other");
}
原文：http://www.cnblogs.com/xlsn0w/p/4819187.html