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
No Match

/
/
gm

Test String

Substitution

Processing...

Code Generator

Language

Generated Code

$re = '/(?i)^(?!((<\/|<)(h[1-6]|ul|li|script|blockquote)(\s.+)*>))(.+)(?!(<(\/\3)>))$/m'; $str = '<h2>Lorem ipsum dolor sit amet, consectetur adipiscing elit</h2> Vivamus vel tempor turpis, <strong>non rutrum quam</strong>. Suspendisse ac rhoncus felis, eget porta lectus. Nam vulputate sapien risus, vel vehicula mi volutpat sed. <ul> <li>Sed feugiat nibh at nisl eleifend scelerisque.</li> <li>Aliquam non maximus ipsum. Aliquam erat volutpat.</li> </ul> <h3>Praesent eget diam sit amet leo vehicula sagittis at quis tortor</h3> Nunc nec sem ac nunc tincidunt aliquam ut nec dolor. Nulla facilisi. <img alt="xxxx" src="xxx.png" class="xxxxx"/> <caption><i>ccccc</i></caption> <img alt="xxxx" src="xxx.png" class="xxxxx"/> <i>ccccc</i> <strong>Nunc nec sem ac nunc tincidunt aliquam ut nec dolor. Nulla facilisi.</strong> Vivamus vel tempor turpis, <strong>non rutrum quam</strong>. Suspendisse ac rhoncus felis, eget porta lectus. Nunc nec Nunc nec Nunc nec <blockquote class="twitter-tweet" data-lang="en"><p lang="en" dir="ltr">Vivamus vel tempor turpis <a href=""></a></p>&mdash; xxxxx (@xxxxxx) <a href="https://twitter.com/xxxx/status/x?ref_src=x">February 15, 2019</a></blockquote> <script async src="" charset="utf-8"></script>'; $subst = "<p>$5</p>"; $result = preg_replace($re, $subst, $str); echo "The result of the substitution is ".$result;

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