Regular Expression Basics

WARNING: This page may seem redundant to you, since there are a lot of other resources on this available.

. Placeholder for any character

* Modifier for any number of characters from 0 to probably "2 to the power of 32"[Roughly 4 billion] on most machines.

+ Modifier for any number of characters from 1 to probably "2 to the power of 32"[Roughly 4 billion] on most machines.

? Modifier for either one or none character of the aforementioned kind.

| OR: Conjugation of different word-definitions. For example: a|fooBar filters words that are either just "a" or "fooBar"

^ NOT the following sign. For example: [^1] means any character but 1.

() are used for grouping characters. For example ...(....)? means that the words have to be either 3 or 7 chars long, since the question-mark defines the "4 Chars extra" as either there or not.

Random Examples:

.* characterizes any word, even the empty word.

...+ characterizes any word, that is at least three character long.

[^word]* characterizes any word that DOES NOT include the small letters w, o, r or d.