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PHP Regex

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This commit is contained in:
Vishalghyv 2020-10-06 15:55:29 +05:30
parent 5502ffd277
commit 20594479f3
1 changed files with 103 additions and 1 deletions
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104
languages/php.php
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@ -331,7 +331,6 @@ abstract class AbstractClassName
}
/**
* Basic Implementation of LoggerAwareInterface.
* @see https://github.com/php-fig/log/blob/master/Psr/Log/LoggerAwareTrait.php
@ -366,3 +365,106 @@ class ClassWithLogger
*/
use LoggerAwareTrait;
}
/**
* PHP Regex.
*/
// Meta Characters.
^ Start of subject (or line in multiline mode)
$ End of subject (or line in multiline mode)
[ Start character class definition
] End character class definition
| Alternates, eg (a|b) matches a or b
( Start subpattern
) End subpattern
\ Escape character
// Pattern Modifiers.
i Caseless - ignore case
m Multiline mode - ^ and $ match start and end of lines
s Dotall - . class includes newline
x Extended- comments & whitespace
e preg_replace only - enables evaluation of replacement as PHP code
S Extra analysis of pattern
U Pattern is ungreedy
u Pattern is treated as UTF-8
// Subpattern Modifiers & Assertions.
(?:) Non capturing subpattern ((?:foo|fu)bar) matches foobar or fubar without foo or fu appearing as a captured subpattern
(?=) Positive look ahead assertion foo(?=bar) matches foo when followed by bar
(?!) Negative look ahead assertion foo(?!bar) matches foo when not followed by bar
(?<=) Positive look behind assertion (?<=foo)bar matches bar when preceded by foo
(?<!) Negative look behind assertion (?<!foo)bar matches bar when not preceded by foo
(?>) Once-only subpatterns (?>\d+)bar Performance enhancing when bar not present
(?(x)) Conditional subpatterns (?(3)foo|fu)bar Matches foo if 3rd subpattern has matched, fu if not
(?#) Comment (?# Pattern does x y or z)
// Base Character Classes
\w Any "word" character (a-z 0-9 _)
\W Any non "word" character
\s Whitespace (space, tab CRLF)
\S Any non whitepsace character
\d Digits (0-9)
\D Any non digit character
. (Period) - Any character except newline
// Multiplicity.
n* Zero or more of n
n+ One or more of n
n? Zero or one occurrences of n
{n} n occurrences exactly
{n,} At least n occurrences
{,m} At most m occurrences
{n,m} Between n and m occurrences (inclusive)
// PHP Regular Expression Functions.
Function Description
preg_match() The preg_match() function searches string for pattern, returning true if pattern exists, and false otherwise.
preg_match_all() The preg_match_all() function matches all occurrences of pattern in string. Useful for search and replace.
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.
preg_split() Preg Split (preg_split()) operates exactly like the split() function, except that regular expressions are accepted as input parameters.
preg_grep() The preg_grep() function searches all elements of input_array, returning all elements matching the regex pattern within a string.
preg_ quote() Quote regular expression characters
// Code Snippets.
//A better solution for validate email syntax is using filter_var.
if (filter_var('test+email@fexample.com', FILTER_VALIDATE_EMAIL)) {
echo "Your email is ok.";
} else {
echo "Wrong email address format.";
}
//Validate username, consist of alpha-numeric (a-z, A-Z, 0-9), underscores, and has minimum 5 character and maximum 20 character.
//You could change the minimum character and maximum character to any number you like.
$username = "user_name12";
if (preg_match('/^[a-z\d_]{5,20}$/i', $username)) {
echo "Your username is ok.";
} else {
echo "Wrong username format.";
}
//Validate domain
$url = "http://domain-name.com/";
if (preg_match('/^(http|https|ftp):\/\/([A-Z0-9][A-Z0-9_-]*(?:\.[A-Z0-9][A-Z0-9_-]*)+):?(\d+)?\/?/i', $url)) {
echo "Your url is ok.";
} else {
echo "Wrong url.";
}
//Extract domain name from certain URL
$url = "http://domain-name.com/index.html";
preg_match('@^(?:http://)?([^/]+)@i', $url, $matches);
$host = $matches[1];
echo $host; // domain-name.com
//Highlight a word in the content
$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.";
$text = preg_replace("/\b(regex)\b/i", 'replaced content', $text);
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.*/