Regular Expressions 101

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/
(?<=^|;|<\?php\s|<\?\s)(\s*?)(\h*\$(\w+)\s*=)(\s*([\'"].*?[\'"]|.*?)\s*;)
/
imsg
Positive Lookbehind
(?<=^|;|<\?php\s|<\?\s)
Assert that the Regex below matches
1st Alternative
^
^ asserts position at start of a line
2nd Alternative
;
; matches the character ; with index 5910 (3B16 or 738) literally (case insensitive)
3rd Alternative
<\?php\s
< matches the character < with index 6010 (3C16 or 748) literally (case insensitive)
\? matches the character ? with index 6310 (3F16 or 778) literally (case insensitive)
php
matches the characters php literally (case insensitive)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
4th Alternative
<\?\s
< matches the character < with index 6010 (3C16 or 748) literally (case insensitive)
\? matches the character ? with index 6310 (3F16 or 778) literally (case insensitive)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
1st Capturing Group
(\s*?)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
2nd Capturing Group
(\h*\$(\w+)\s*=)
\h
matches any horizontal whitespace character (equivalent to [[:blank:]])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\$ matches the character $ with index 3610 (2416 or 448) literally (case insensitive)
3rd Capturing Group
(\w+)
\w
matches any word character (equivalent to [a-zA-Z0-9_])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
= matches the character = with index 6110 (3D16 or 758) literally (case insensitive)
4th Capturing Group
(\s*([\'"].*?[\'"]|.*?)\s*;)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
5th Capturing Group
([\'"].*?[\'"]|.*?)
1st Alternative
[\'"].*?[\'"]
Match a single character present in the list below
[\'"]
\' matches the character ' with index 3910 (2716 or 478) literally (case insensitive)
" matches the character " with index 3410 (2216 or 428) literally (case insensitive)
.
matches any character
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
Match a single character present in the list below
[\'"]
\' matches the character ' with index 3910 (2716 or 478) literally (case insensitive)
" matches the character " with index 3410 (2216 or 428) literally (case insensitive)
2nd Alternative
.*?
.
matches any character
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v ])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
; matches the character ; with index 5910 (3B16 or 738) literally (case insensitive)
Global pattern flags
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
s modifier: single line. Dot matches newline characters
g modifier: global. All matches (don't return after first match)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
imsg

Test String

Code Generator

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Generated Code

Loading code sample...
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report.
For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php

Regular Expressions 101

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