> POSIX character classes for creating regular expressions.
## Install
Install with [npm](https://www.npmjs.com/):
```sh
$ npm install --save posix-character-classes
```
Install with [yarn](https://yarnpkg.com):
```sh
$ yarn add posix-character-classes
```
## Usage
```js
var posix = require('posix-character-classes');
console.log(posix.alpha);
//=> 'A-Za-z'
```
## POSIX Character classes
The POSIX standard supports the following classes or categories of charactersh (note that classes must be defined within brackets)<supclass="footnote-ref"><ahref="#fn1"id="fnref1">[1]</a></sup>:
| `[:blank:]` | `[ \t]` | space and TAB characters only |
| `[:cntrl:]` | `[\x00-\x1F\x7F]` | Control characters |
| `[:digit:]` | `[0-9]` | digits |
| `[:graph:]` | `[^[:cntrl:]]` | graphic characters (all characters which have graphic representation) |
| `[:lower:]` | `[a-z]` | lowercase letters |
| `[:print:]` | `[[:graph] ]` | graphic characters and space |
| `[:punct:]` | ``[-!"#$%&'()*+,./:;<=>?@[]^_`{ | }~]`` | all punctuation characters (all graphic characters except letters and digits) |
| `[:space:]` | `[ \t\n\r\f\v]` | all blank (whitespace) characters, including spaces, tabs, new lines, carriage returns, form feeds, and vertical tabs |
*`a[:digit:]b` is invalid, character classes must be enclosed in brackets
*`[[:digit:]abc]` matches any digit, as well as `a`, `b`, and `c`.
*`[abc[:digit:]]` is the same as the previous, matching any digit, as well as `a`, `b`, and `c`
*`[^ABZ[:lower:]]` matches any character except lowercase letters, `A`, `B`, and `Z`.
## About
### Contributing
Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
### Building docs
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<hrclass="footnotes-sep">
<sectionclass="footnotes">
<olclass="footnotes-list">
<liid="fn1"class="footnote-item">table and examples are based on the WikiBooks page for [Regular Expressions/POSIX Basic Regular Expressions](https://en.wikibooks.org/wiki/Regular_Expressions/POSIX_Basic_Regular_Expressions), which is available under the [Creative Commons Attribution-ShareAlike License](https://creativecommons.org/licenses/by-sa/3.0/). <ahref="#fnref1"class="footnote-backref">↩</a>