Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
Processing...

Test String

Code Generator

Generated Code

$re = '/^^(?![^?\n]*\?)(?!.*(interpersonal\.meta\.stackexchange\.com)).*good\s+answer/m'; $str = 'Here are the strings I want to detect: -------------------------------------- That a very good answer! (Other than that, this is a really good answer and I\'ve upvoted it.) good answer dvdf! dsds good answer cfds It is a good answer, but I feel it played into the OP\'s hands really. You said what they wanted to hear - that they shouldn\'t freely share the information because it is like a child cheating on their homework. It is contrary to the spirit of this site, and I\'m not sure that charging a colleague money to learn something work-based from you won\'t get the OP into trouble with their employer. Imagine if a doctor asked to confer with a fellow doctor in order to help a patient, and they charged each other for the information they shared. They\'d be dismissed. Here are the one I don\'t want to detect ----------------------------------------- Thanks for this good answer! (I upvoted it) However, I still don\'t understand why I shouldn\'t mention that I believe whatever? What\'s the problem with that... cxvd good answer? zedfs ezdds? good answer dsf dsf sdsd? dsfdsf? good answer! Hi, the question is "How to tell blabla when X is my good friend", would you mind be a little more detail about how OP should do that when OP still want to be friend with both parties? Also, please take some time to read "How do I write a good answer As a side note, here is a link to "How do I write a good answer? Hi, this sound like a good answer to me, I just have one question though: Where you in a similar situation before where you successfully used this technic? In here it\'s better to back-up your answer with personal experience (here is a guide to How to write a good answer if you need it) New formule -------------- Hey, welcome to IPS! At the time being, your answer doesn\'t seem to actually address the question and is likely to get deleted. However, you can still edit it after reading "<a href="https://interpersonal.meta.stackexchange.com/q/3266/21067">How to write a good answer</a>" to try to make the answer up to your standards. On a side note, here is a link to "[How to write a good answer](https://interpersonal.meta.stackexchange.com/q/3266/21067)" and here is one to the [help center](https://interpersonal.stackexchange.com/help/how-to-answer). '; preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0); // Print the entire match result var_dump($matches);

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