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

/
/
g

Test String

Code Generator

Language

Generated Code

$re = '/Content-Transfer-Encoding:\sbase64\s+(.*)(?=Content-Transfer-Encoding: base64|$)/'; $str = 'Content-Transfer-Encoding: base64 DQoNCg0KDQoNCg0KDQoNCg0KDQpbQiZRXTxodHRwOi8vd3d3LmRpeS5jb20+DQoNCg0KDQoNCg0K W2h0dHA6Ly9raW5nZmlzaGVyLnNjZW5lNy5jb20vaXMvaW1hZ2UvS2luZ2Zpc2hlci9pY29uX3N0 b3JlX2xvY2F0b3I/d2lkPTM2JmhlaT0zNiZxbHQ9MTAwXTxodHRwOi8vd3d3LmRpeS5jb20vZmlu ZC1hLXN0b3JlPg0KDQoNCg0KRmluZCBhIHN0b3JlPGh0dHA6Ly93d3cuZGl5LmNvbS9maW5kLWEt c3RvcmU+DQoNCg0KDQoNCkN1c3RvbWVyIFNlcnZpY2VzDQoNCjAzMzMgMDE0IDMzNTcNCg0KDQoN Cg0KDQoNCg0KDQoNCkluc3BpcmF0aW9uPGh0dHA6Ly93d3cuZGl5LmNvbS9pbnNwaXJhdGlvbi8w Lmlyb290Pg0KDQpQcm9qZWN0czxodHRwOi8vd3d3LmRpeS5jb20vcHJvamVjdHMvMi5wcm9vdD4N Cg0KU2hvcDxodHRwOi8vd3d3LmRpeS5jb20vc2hvcC8+DQoNCkhlbHAgJiBBZHZpY2U8aHR0cDov L3d3dy5kaXkuY29tL2hlbHAtYWR2aWNlLzEuaHJvb3Q+DQoNCk15IGFjY291bnQ8aHR0cDovL3d3 dy5kaXkuY29tL2N1c3RvbWVyL215X2FjY291bnQvPg0KDQoNCg0KDQoNCg0KDQoNCg0KRGVhciBC ZW4gUGF0b24NCg0KDQoNCg0KVGhhbmsgeW91IGZvciB5b3VyIG9yZGVyDQoNCg0KDQoNCg0KT3Jk ZXIgbnVtYmVyOg0KDQowMDYzMTA5MDU1DQoNCg0KDQpUb3RhbCBDb3N0Og0KDQrCozMuMjcNCg0K DQoNClRoYW5rIHlvdSBmb3Igb3JkZXJpbmcgZnJvbSBCJlEuIFlvdeKAmWxsIGZpbmQgZGV0YWls cyBvZiB5b3VyIG9yZGVyIGFuZCBkZWxpdmVyeSBvciBjb2xsZWN0aW9uIGluZm9ybWF0aW9uIGJl bG93LiBGb3IgaGVscCB3aXRoIHF1ZXN0aW9ucyBhYm91dCBvdXIgc2VydmljZSwgcGxlYXNlIHNl--_000_D16F6E4A2986D34F9D752E3564EAC46F51043449APP1198ghakfplc_ Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: base64 PGh0bWwgeG1sbnM6dj0idXJuOnNjaGVtYXMtbWljcm9zb2Z0LWNvbTp2bWwiIHhtbG5zOm89InVy bjpzY2hlbWFzLW1pY3Jvc29mdC1jb206b2ZmaWNlOm9mZmljZSIgeG1sbnM6dz0idXJuOnNjaGVt YXMtbWljcm9zb2Z0LWNvbTpvZmZpY2U6d29yZCIgeG1sbnM6bT0iaHR0cDovL3NjaGVtYXMubWlj cm9zb2Z0LmNvbS9vZmZpY2UvMjAwNC8xMi9vbW1sIiB4bWxucz0iaHR0cDovL3d3dy53My5vcmcv '; preg_match_all($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