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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

/
/
xgm

Test String

Code Generator

Generated Code

$re = '/(?<=[ \t])-? (?: (?: \d |[1-9]\d+ |[1-9]\d*\.\d{1,3}(?<!0) |\.\d{1,3}(?<!0) )|(?: (\.0*)0 |(0+)\.\d{0,2}[1-9] |(0+)(?:0|[1-9]\d*)\.?\d* |\d+(\.0*) |\d*\.(?:[1-9]|\d[1-9])?(0+) |\d*\.\d{3}(\d+) ) ) (?=[ \t]|$)[ \t]?/xm'; $str = 'Valid: * Integers 0 1 10 123 -0 -1 -10 -123 * Floats <1, without leading zero, (1<=precision<=3) .1 .01 .001 .12 .123 -.1 -.01 -.001 -.12 -.123 * Floats >1, (1<=precision<=3) 1.1 1.01 1.001 1.12 1.123 12.1 12.12 12.123 123.1 123.12 123.123 -1.1 -1.01 -1.001 -1.12 -1.123 -12.1 -12.12 -12.123 -123.1 -123.12 -123.123 Invalid (in order of capture): * [1] Zero as float with only trailing zeros .0 .00 .000 -.0 -.00 -.000 * [2] Floats <1, with leading zero 0.1 0.01 0.001 0.12 0.123 -0.1 -0.01 -0.001 -0.12 -0.123 * [3] Integers with leading zeros 00 01 012 0123 000 001 0012 00123 0000 0001 00012 000123 -00 -01 -012 -0123 -000 -001 -0012 -00123 -0000 -0001 -00012 -000123 * [4] Integers as float (\'fake floats\') 0. 1. 12. 123. 0.0 0.00 0.000 0.0000 1.0 1.00 1.000 -0. -1. -12. -123. -0.0 -0.00 -0.000 -0.0000 -1.0 -1.00 -1.000 * [5] Floats with trailing zeros 1.10 1.100 1.120 .10 .100 .120 -1.10 -1.100 -1.120 -.10 -.100 -.120 * [6] Any float with precision >3 0.0001 0.0012 0.0123 0.1234 1.0001 1.0012 1.0123 1.1234 10.0001 10.0012 10.0123 10.1234 100.0001 100.0012 100.0123 100.1234 -0.0001 -0.0012 -0.0123 -0.1234 -1.0001 -1.0012 -1.0123 -1.1234 -10.0001 -10.0012 -10.0123 -10.1234 -100.0001 -100.0012 -100.0123 -100.1234 '; preg_match_all($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