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 = str.gsub(re, subst) # Print the result of the substitution puts 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 Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html