Regular expression quick start guide

Quick Reference Table

Regular Expression Pattern	Explanations	Examples
Meta characters  [\^$.|?*+(	Special caracters used in regex. Must be escape with backslash "\" to use a literal characters.
Literal characters	All characters (except the metacharacters) match a single instance of themselves. { and } are literal characters, unless they're part of a valid regular expression token (e.g. the {n} quantifier).	/a/ matches "a"
^	Matches beginning of a line
$	Matches the end of a line
\d	Matches a digit
[characters]	Matches any single character between the brackets
re1|re2	Match either re1 or re2
re*	Matches zero or more occurrences of re
re+	Matches one or more occurrences of re
re?	Matches zero or one occurrences of re
Re{m,n}	Matches at least “m” and at most “n” occurrences of re
(...)	Parentheses are used to group regular expressions
\0, \1, \2, ...	Substitute the value matched by the nth grouped sub-expression, used in remapped fields.

Examples

Here are some examples:

Add 2720 prefix:

/(\d+)/2720\1/

or

/([0-9]*)/2720\1/

Strip first 4 digits:

/([0-9]{4})([0-9]*)/\2/

Strip # and 7 first digits:

/([#])([0-9]{7})([0-9]*)/\3/

Web Online Tools

• Regular builder tool : www.gskinner.com/RegExr
• Ruby regular expression editor and tester : rubular.com
  

References

• How to Use RegEx in Called and Calling Number Mask
• How to Use RegEx in Remapped Called and Calling Number Mask