In PHP

Regular Expressions are used to do pattern matching PHP ,supports two types of pattern matching POSIX and PERL type.

Regular Expressions are used to do pattern matching

PHP ,supports two types of pattern matching POSIX and PERL type.

Caret(^)at the beginning of regular expression: Indicates string begin searched must start with this pattern. Ex. ^woo will search “woo”,”wood”, “woooo” but not “wow”

Caret(^)at the beginning of regular expression: Indicates string begin searched must start with this pattern.

Ex.

^woo will search “woo”,”wood”, “woooo”

but not “wow”

Contd.. Dollar($)at end of regular expression : Indicates that string being searched must end with this pattern. Ex. bie$ will search “barbie”,”newbie” but not “biebar”

Dollar($)at end of regular expression : Indicates that string being searched must end with this pattern.

Ex.

bie$ will search “barbie”,”newbie”

but not “biebar”

Contd.. Questionmark(?) :Indicates that preceding character should appear ZERO or ONE times in pattern/searched string Ex: wo? will search “wd”,”wod” but not “wood”

Questionmark(?) :Indicates that preceding character should appear ZERO or ONE times in pattern/searched string

Ex:

wo? will search “wd”,”wod” but not “wood”

Contd.. Plus(+):Indicates that preceding character should appear ONE or MORE times in pattern. Ex. wo+ will search “wo”,”woo”,”wow” but not “wa”

Plus(+):Indicates that preceding character should appear ONE or MORE times in pattern.

Ex.

wo+ will search “wo”,”woo”,”wow” but not “wa”

Contd.. Asterisk(*):Indicates that preceding character should appear ZERO or MORE times in pattern. Ex. wo* will search “w”,”wo”,”wood”,”wd”

Asterisk(*):Indicates that preceding character should appear ZERO or MORE times in pattern.

Ex.

wo* will search “w”,”wo”,”wood”,”wd”

Contd.. {n}:Indicates that preceding character should appear exactly “n” times in pattern. Ex. wo{3} will search “wooo” but not “woooo”

{n}:Indicates that preceding character should appear exactly “n” times in pattern.

Ex.

wo{3} will search “wooo” but not “woooo”

Contd.. {n1,n2}:Indicates that preceding character should appear in pattern atleast “n1” times and atmax “n2” times. Ex. wo{2,4}d will search “wood”,”woood”,”woood” but not “wod”

{n1,n2}:Indicates that preceding character should appear in pattern atleast “n1” times and atmax “n2” times.

Ex.

wo{2,4}d will search “wood”,”woood”,”woood” but not “wod”

Contd.. {n,}:Indicates that preceding character should appear in pattern atleast “n” times but no maximum limit . Ex. wo{2,}d will search “wood”,”woood” but not “wod”

{n,}:Indicates that preceding character should appear in pattern atleast “n” times but no maximum limit .

Ex.

wo{2,}d will search “wood”,”woood”

but not “wod”

Contd.. Dot(.):Indicates any character except newline. Ex. wo.d will search “woad”,”wo9d”,”wo d” but not “wo
d”

Dot(.):Indicates any character except newline.

Ex.

wo.d will search “woad”,”wo9d”,”wo d”

but not “wo
d”

Contd.. Backslash-d(d) : Indicates any digit [0-9] Ex. “ wodd” will search “wo3d”,”wo7d” but not “woad”

Backslash-d(d) : Indicates any digit [0-9]

Ex.

“ wodd” will search “wo3d”,”wo7d”

but not “woad”

Contd.. Backslash-D(D): Indicates any character except digit [^0-9] Ex. woDd will search “woad”,”wo@d” but not “wo2d”

Backslash-D(D): Indicates any character except digit [^0-9]

Ex.

woDd will search “woad”,”wo@d”

but not “wo2d”

Contd.. Backslash-w(w):Indicates any character, digit and underscore(_) Ex. “ wowd” will search “wo0d”,”wo_d”,”woud” but not “wo&d”

Backslash-w(w):Indicates any character, digit and underscore(_)

Ex.

“ wowd” will search “wo0d”,”wo_d”,”woud” but not “wo&d”

Contd.. Backslash-W(w): Indicates any character except letter, digit and underscore(_) Ex. woWd will search “wo%d”,”wo@d” but not “wood” or “wo8d”

Backslash-W(w): Indicates any character except letter, digit and underscore(_)

Ex.

woWd will search “wo%d”,”wo@d” but not “wood” or “wo8d”

Contd.. Backslash-s(s):Indicates any white space i.e. newline , tab , space Ex. “ wosd” will search “wo d”, “wo d” but not “wood”

Backslash-s(s):Indicates any white space i.e. newline , tab , space

Ex.

“ wosd” will search “wo d”, “wo d” but not “wood”

Contd.. Backslash-S(S):Indicates any character except white spaces i.e. space , tab , newline Ex. “ woSd” will search “wo@d”, “wood” but not “wo d”

Backslash-S(S):Indicates any character except white spaces i.e. space , tab , newline

Ex.

“ woSd” will search “wo@d”, “wood” but not “wo d”

Contd.. Grouping[]:Indicates group of options Ex. wo[aeiou]d will search “woad”, “woed” ,“woud” but not “wobd” wo[aeiou]{2}d will search “woaed”, “wooud”, “woiud” but not “woaeioud”

Grouping[]:Indicates group of options

Ex.

wo[aeiou]d will search “woad”, “woed” ,“woud” but not “wobd”

wo[aeiou]{2}d will search “woaed”, “wooud”, “woiud” but not “woaeioud”

Contd.. Negotiation(^):Indicates not this group of options. Ex. “ wo[^aeiou]d” will search “wobd”, “wo8d” but not “woad”

Negotiation(^):Indicates not this group of options.

Ex.

“ wo[^aeiou]d” will search “wobd”, “wo8d” but not “woad”

Contd.. Pipe(|):Indicates options for pattern. Ex. woo$ | ^cut will search “cutabcfoo” , “cutwoo” ,“abcwoo”, “cutabc” but not “woocut”

Pipe(|):Indicates options for pattern.

Ex.

woo$ | ^cut will search “cutabcfoo” , “cutwoo” ,“abcwoo”, “cutabc” but not “woocut”

Contd.. Backslash(): to escape character. Ex. wo.d will search “wo.d” wo\h will search “woh”

Backslash(): to escape character.

Ex.

wo.d will search “wo.d”

wo\h will search “woh”

Contd.. Parenthesis(()):Indicates sub pattern Ex. w(oo)?d will search “wood” , “wd”

Parenthesis(()):Indicates sub pattern

Ex.

w(oo)?d will search “wood” , “wd”

PHP PCRE FUNCTIONS preg_match() : Perform a regular expression match. preg_match_all() : Perform a global regular expression match preg_replace() : Perform a regular expression search and replace preg_split() : Split string by a regular expression preg_grep () : Return array entries that match the pattern

preg_match() : Perform a regular expression match.

preg_match_all() : Perform a global regular expression match

preg_replace() : Perform a regular expression search and replace

preg_split() : Split string by a regular expression

preg_grep () : Return array entries that match the pattern

REFERENCE http://in.php.net/manual/

http://in.php.net/manual/