Am I the only person who thinks that things like this are totally unnecessary? Is learning/reading regular expressions really that difficult for most people?
Here's the subset of regular expressions that has gotten me through nearly all of the regular expressions I've ever needed to write. As a plus, it has no dependencies!
* - zero or more of the preceding character/group
+ - one or more of the preceding character/group
? - zero or one of the preceding character/group
$ - end of line
^ - beginning of line
. - one of any one character
\ - escape the following character (for a literal '$' or '.', for example)
[<some characters>] - one of the given characters
[a-zA-Z0-9] - letters and numbers inside a group can have ranges!
(<something>) - capturing group (anything that matches inside it will be accessible in the match object)
<thing1>|<thing2> - either the first thing, or the second thing (or the third, or the fourth...)
This isn't a complete, or even precise, definition, but knowing those things will get you to the point where you can read and write expressions like this:
^(-|+)?[0-9]*\.[0-9]+$
which matches things like -.2, 0.123, +0.1, etc. (floating point numbers, basically). This likely has bugs, since I haven't tested it ;)
Here's the subset of regular expressions that has gotten me through nearly all of the regular expressions I've ever needed to write. As a plus, it has no dependencies!
* - zero or more of the preceding character/group
+ - one or more of the preceding character/group
? - zero or one of the preceding character/group
$ - end of line
^ - beginning of line
. - one of any one character
\ - escape the following character (for a literal '$' or '.', for example)
[<some characters>] - one of the given characters
[a-zA-Z0-9] - letters and numbers inside a group can have ranges!
(<something>) - capturing group (anything that matches inside it will be accessible in the match object)
<thing1>|<thing2> - either the first thing, or the second thing (or the third, or the fourth...)
This isn't a complete, or even precise, definition, but knowing those things will get you to the point where you can read and write expressions like this:
^(-|+)?[0-9]*\.[0-9]+$
which matches things like -.2, 0.123, +0.1, etc. (floating point numbers, basically). This likely has bugs, since I haven't tested it ;)