| POSIX | Perl | ASCII | Description |
|---|
[:alnum:] |
| [A-Za-z0-9] | Alphanumeric characters |
[:word:] | \w | [A-Za-z0-9_] | Alphanumeric characters plus "_" |
| \W | [^\w] | non-word character |
[:alpha:] |
| [A-Za-z] | Alphabetic characters |
[:blank:] |
| [ \t] | Space and tab |
[:cntrl:] |
| [\x00-\x1F\x7F] | Control characters |
[:digit:] | \d | [0-9] | Digits |
| \D | [^\d] | non-digit |
[:graph:] |
| [\x21-\x7E] | Visible characters |
[:lower:] |
| [a-z] | Lowercase letters |
[:print:] |
| [\x20-\x7E] | Visible characters and spaces |
[:punct:] |
| [-!"#$%&'()*+,./:;<=>?@[\\\]_`{|}~] | Punctuation characters |
[:space:] | \s | [ \t\r\n\v\f] | Whitespace characters |
| \S | [^\s] | non-whitespace character |
[:upper:] |
| [A-Z] | Uppercase letters |
[:xdigit:] |
| [A-Fa-f0-9] | Hexadecimal digits |
