Regular expression basics

Regular expressions use special characters (also known as regular expression operators) to specify rules for strings. A summary of these characters are:

^        Beginning of string

$        End of string

.        Any character

[        Start of character list

]        End of character list

(        Start of expression group

)        End of expression group

|        ORs two expressions

\        Escape character

*        Preceding expression occurs zero or more times

?        Preceding expression occurs zero or one times

+        Preceding expression occurs one or more times