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

Code Generator

Language

Generated Code

$re = '/U{2,3}D{2,3}(?!D)|D{2,3}U{2,3}(?!U)/m'; $str = 'Good UUDDDUUU Bad UDUDUDUU Bad DUDUDDDU Bad UDDUDUDU Bad UDUUUDDD Bad DDUDDUDD Good UUDDUUUU Bad UUUUDUUD Bad DUUDUDUD Good UDDUUUDU Bad DDDDUDDD Bad DUUUUDDU Bad UUUUUUUD Good DUUDDDUD Bad DDDDUUUU Good DDDUUDUU Bad UDUDDUUD Bad DDDDDDDD Good DUUUDDDU Bad DDDDDUUU Bad DDUUUUUD Bad UDUUDUDU Bad DDDUDDUU Bad UDUDUUUD Bad DUDUUUDU Good DDUUDUUD Bad UDUUUUDU Bad DDUDUDDD Bad DUDUDUDU Bad UDDUDDDU Bad DDUDDDDD Bad DUUDUUUD Good UDDUUDDU Bad DUUUUUDU Good DUUDDUUD Bad DDDDUDUU Bad UDUDDDUD Bad DUUUDUDU Bad DDDDDDUU Good DDUUUDUD Bad UDUUDDDU Bad UDUDUDUD Good DDUUDDUD Bad UDUUUDDU Bad DUDDUDDU Bad UUDDDDUD Bad DUDUUDUD Bad DUDDDDDU Good UUDDUDUD Bad UUUUDDUU Bad UDDDDUDU Bad DUDUDDUD Bad UUUUUDUU Bad UDDUDUUD Good UDDDUUDU Bad DUUDUDDU Bad UDDUUUUD Bad UUDUDDDD Bad DUUDDDDU Bad UDUDDUDU Bad UUDUUDDD Bad DUDDUUDU Good UUDDDUUD Bad UDUDUUDU Bad DUDUUUUD Good UUUDDDUU Bad DUDDDUDU Good UUDDUUUD Bad UUUUDUUU Bad UDDDDDDU Bad UUUUDDDD Bad DUDUDUUD Bad UUUDUDUU Bad UUUUUUUU Bad UDDUDDUD Bad DDDDUUUD Bad UDDDUDDU Bad UUUUUDDD Bad DUUDUUDU Good UDDUUDUD Bad DDDDDUUD Bad DDUUUUUU Bad UUDUDUDD Bad DUDDUDDD Good DUUDDUDU Bad UDUDDDDU Good DDUUDUUU Bad DUDUUDUU Bad UUDUUUDD Bad DUDDDDDD Bad UDDDDUDD Bad UDUDUDDU Bad DUDUDDUU Good UUUDDUUU Good DDDUUUDD Bad UDDUDUUU Good UDDDUUDD Bad UUUUDUDD Bad DUUDUDDD Bad UUUDUUUU Bad DDDUDUDD Bad UDDUUUUU Bad DDDDUDUD Bad UUDUDDDU Bad UUUUUUDD Bad DUUDDDDD Bad DDUDUUUU Bad UDUDDUDD Bad DDDDDDUD Bad UUDUUDDU Good DDUUUDUU Bad DUDDUUDD Bad DDUUUUDD Bad DDUDDUUU Bad DUDDUDUU Bad UDUDUUDD Good DDUUDDUU Bad DUDUUUUU Good UUUDDDUD Bad DUDDDUDD Good DDUUDUDD Bad UDDDDDDD Bad DUDDDDUU Bad DUUUUDUD Bad UUUUDDDU Bad DUDUDUUU Bad UUUDUDUD Bad UDDDDUUU Good DDDUUDDD Bad UDDUDDUU Bad UDDDUDDD Good DUUUDDUD Bad UUUUUDDU Bad DUUDUUDD Bad UDDDUUUU Bad UDUUDUUD Bad DDDUDDDD Good UDDUUDUU Bad UUDUDUDU Good DUUDDUDD Bad UDUUUUUD Bad DDUDUDUU Bad UDUDDDDD Bad UUDUUUDU Good DDUUUDDD Bad DDUDDDUU Bad DUDDUUUU Bad UDUDUDDD Good UUUDDUUD Good DDDUUUDU Good DDUUDDDD Bad DUDDDUUU Bad DUUUUUUD Bad UUUUDUDU Bad UUUDUUUD Bad DDDUDUDU Bad UDDDDDUU Bad DUUUDUUD Bad UUUUUUDU Bad UDDDUDUU Bad UDUUDDUD Bad DDUDUUUD Bad DDUUUUDU Bad UDUUUDUD Bad DDUDDUUD Good DDUUDUDU Good DDDUUDDU Bad DDDUDDDU Bad DDUDUDUD Good DDUUUDDU Bad DDUDDDUD Good DDUUDDDU Bad UUDDDDDU Bad UUDUDDUD Good UUDDUDDU Bad UUDUUDUD Bad UUUDDDDU Bad UUUDUDDU Good UUDDDUDU Bad UUDUDUUD Bad DUDDUDUD Good UUDDUUDU Bad UUDUUUUD Bad DUDDDDUD Bad DUUUUDUU Bad DDDDUUDU Bad UDDDDUUD Good UUUDDUDU Good DUUUDDUU Bad DDDUUUUD Bad DDDDDUDU Good UDDDUUUD Bad UDUUDUUU Bad UUDDDDDD Bad UUUDUUDU Bad DDDUDUUD Bad DUDUUDDD Bad UUDUDDUU Bad UDUUUUUU Good UUDDUDDD Bad DDUDUUDU Bad DUDUDDDD Bad UUDUUDUU Bad DUDDUUUD Bad UDDUDUDD Bad DDUDDUDU Bad DUUDUDUU Bad UUUDDDDD Bad DUDDDUUD Bad DUUUUUUU Good UDDUUUDD Bad DDDDUDDU Bad UDDDDDUD Bad DUUUUDDD Good DUUDDDUU Bad UUUDUDDD Bad DUUUDUUU Good DDDUUDUD Bad UDUDDUUU Bad DDDDDDDU Bad UDDDUDUD Bad UDUUDDUU Good UUDDDUDD Bad DUUUDDDD Bad UDUUDUDD Bad DDDUDDUD Bad UUDDDDUU Bad UDUDUUUU Bad DUDUUUDD Bad UUDUDUUU Bad UDUUUDUU Good UUDDUUDD Bad UDUUUUDD Good UUDDUDUU Bad DDUDUDDU Bad UUUUDDUD Bad DUDUDUDD Bad UUDUUUUU Bad DDDDUUDD Bad UDDUDDDD Bad DDUDDDDU Bad UUUUUDUD Bad DUUDUUUU Good UUUDDUDD Bad DDDUUUUU Bad DDDDDUDD Good UDDUUDDD Bad DUUUUUDD Good DUUDDUUU Bad UUUDUUDD Bad DDDUDUUU Bad UDUDDDUU Bad DUDUUDDU Bad DUUUDUDD Bad UDUUDDDD Bad DDUDUUDD'; 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