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

/
/
gmx

Test String

Code Generator

Language

Generated Code

$re = '/<!ELEMENT\s+ ((?\'elname\'\S+)\s+) ((?\'rank\'\d+)\s+)? (?\'tagOmit\' (?\'start\'[-oO])\s+ (?\'end\'[-oO])\s+ )? (?\'content\' (?\'keyword\'(ANY|EMPTY|CDATA|RDATA))| (?\'contentGrp\' \(.*\)[*+?]?) ) (?\'exceptions\' (\s+\-(?\'exclusion\'\(.+\)))? (\s+\+(?\'inclusion\'\(.+\)))? ) \s*>/mx'; $str = '<!ELEMENT FTNOTE - - ((PARA | PARA-EFF-GROUP | PARA-EFF-CHOICE | TABLE | UN-LIST | NOTE | TABLE-EFF-GROUP | TABLE-EFF-CHOICE)+) -(FTNOTE | NOTE | TABLE | GROUND-TEST | CORRECTIVE-ACTION)> <!ELEMENT ENTRY - - (WARNING | CAUTION | NOTE | (PARA | UN-LIST | PARA-EFF-GROUP | PARA-EFF-CHOICE)*) -(ENTRY | GRAPHIC-COLLECTION) +(INFOMARK | FTNOTE-REF)> <!ELEMENT COLSPEC - o EMPTY> <!ELEMENT TGROUP - - (COLSPEC+, THEAD?, TBODY)> <!ELEMENT TABLE - - (TITLE?, TGROUP, FTNOTE*) -(TABLE | TABLE-NO-TITLE | GROUND-TEST | CORRECTIVE-ACTION) +(INFOMARK | INCLUDED-SUBDOC | INCLUDED-SOURCE-DATA | EFF-NONE)>'; preg_match_all($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