Regular Expressions 101

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"
\bStack Overflow\b(?:[^\.]*\.){2}
"
gms
\b assert position at a word boundary: (^\w|\w$|\W\w|\w\W)
Stack Overflow
matches the characters Stack Overflow literally (case sensitive)
\b assert position at a word boundary: (^\w|\w$|\W\w|\w\W)
Non-capturing group
(?:[^\.]*\.){2}
{2} matches the previous token exactly 2 times
Match a single character not present in the list below
[^\.]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
Global pattern flags
g modifier: global. All matches (don't return after first match)
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
Your regular expression does not match the subject string.

Regular Expression
No Match

r"
"
gms

Test String

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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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