PHP Regex
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Vishalghyv
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@ -331,7 +331,6 @@ abstract class AbstractClassName
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}
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/**
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* Basic Implementation of LoggerAwareInterface.
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* @see https://github.com/php-fig/log/blob/master/Psr/Log/LoggerAwareTrait.php
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@ -366,3 +365,106 @@ class ClassWithLogger
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*/
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use LoggerAwareTrait;
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}
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/**
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* PHP Regex.
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*/
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// Meta Characters.
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^ Start of subject (or line in multiline mode)
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$ End of subject (or line in multiline mode)
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[ Start character class definition
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] End character class definition
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| Alternates, eg (a|b) matches a or b
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( Start subpattern
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) End subpattern
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\ Escape character
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// Pattern Modifiers.
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i Caseless - ignore case
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m Multiline mode - ^ and $ match start and end of lines
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s Dotall - . class includes newline
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x Extended- comments & whitespace
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e preg_replace only - enables evaluation of replacement as PHP code
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S Extra analysis of pattern
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U Pattern is ungreedy
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u Pattern is treated as UTF-8
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// Subpattern Modifiers & Assertions.
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(?:) Non capturing subpattern ((?:foo|fu)bar) matches foobar or fubar without foo or fu appearing as a captured subpattern
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(?=) Positive look ahead assertion foo(?=bar) matches foo when followed by bar
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(?!) Negative look ahead assertion foo(?!bar) matches foo when not followed by bar
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(?<=) Positive look behind assertion (?<=foo)bar matches bar when preceded by foo
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(?<!) Negative look behind assertion (?<!foo)bar matches bar when not preceded by foo
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(?>) Once-only subpatterns (?>\d+)bar Performance enhancing when bar not present
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(?(x)) Conditional subpatterns (?(3)foo|fu)bar Matches foo if 3rd subpattern has matched, fu if not
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(?#) Comment (?# Pattern does x y or z)
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// Base Character Classes
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\w Any "word" character (a-z 0-9 _)
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\W Any non "word" character
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\s Whitespace (space, tab CRLF)
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\S Any non whitepsace character
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\d Digits (0-9)
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\D Any non digit character
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. (Period) - Any character except newline
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// Multiplicity.
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n* Zero or more of n
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n+ One or more of n
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n? Zero or one occurrences of n
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{n} n occurrences exactly
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{n,} At least n occurrences
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{,m} At most m occurrences
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{n,m} Between n and m occurrences (inclusive)
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// PHP Regular Expression Functions.
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Function Description
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preg_match() The preg_match() function searches string for pattern, returning true if pattern exists, and false otherwise.
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preg_match_all() The preg_match_all() function matches all occurrences of pattern in string. Useful for search and replace.
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preg_replace() The preg_replace() function operates just like ereg_replace(), except that regular expressions can be used in the pattern and replacement input parameters.
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preg_split() Preg Split (preg_split()) operates exactly like the split() function, except that regular expressions are accepted as input parameters.
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preg_grep() The preg_grep() function searches all elements of input_array, returning all elements matching the regex pattern within a string.
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preg_ quote() Quote regular expression characters
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// Code Snippets.
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//A better solution for validate email syntax is using filter_var.
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if (filter_var('test+email@fexample.com', FILTER_VALIDATE_EMAIL)) {
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echo "Your email is ok.";
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} else {
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echo "Wrong email address format.";
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}
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//Validate username, consist of alpha-numeric (a-z, A-Z, 0-9), underscores, and has minimum 5 character and maximum 20 character.
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//You could change the minimum character and maximum character to any number you like.
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$username = "user_name12";
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if (preg_match('/^[a-z\d_]{5,20}$/i', $username)) {
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echo "Your username is ok.";
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} else {
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echo "Wrong username format.";
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}
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//Validate domain
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$url = "http://domain-name.com/";
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if (preg_match('/^(http|https|ftp):\/\/([A-Z0-9][A-Z0-9_-]*(?:\.[A-Z0-9][A-Z0-9_-]*)+):?(\d+)?\/?/i', $url)) {
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echo "Your url is ok.";
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} else {
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echo "Wrong url.";
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}
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//Extract domain name from certain URL
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$url = "http://domain-name.com/index.html";
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preg_match('@^(?:http://)?([^/]+)@i', $url, $matches);
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$host = $matches[1];
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echo $host; // domain-name.com
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//Highlight a word in the content
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$text = "A regular expression (shortened as regex) is a sequence of characters that define a search pattern. Usually such patterns are used by string-searching algorithms for 'find' or 'find and replace' operations on strings, or for input validation.";
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$text = preg_replace("/\b(regex)\b/i", 'replaced content', $text);
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echo $text; /*A regular expression (shortened as replaced content) is a sequence of characters that define a search pattern. Usually such patterns are used by string-searching algorithms for 'find' or 'find and replace' operations on strings, or for input validation.*/
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