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 = '/["\'`](?:(?<=")[^"\\\\]*(?s:\\\\.[^"\\\\]*)*"|(?<=\')[^\'\\\\]*(?s:\\\\.[^\'\\\\]*)*\'|[^`]*`)/'; $str = 'Almost every SQL statement uses `identifier`s in some way to refer to a database or its constituent elements such as tables, views, columns, indexes, stored routines, triggers, or events. When you refer to elements of databases, `identifier`s must conform to the following rules. Legal characters in `identifier`s. Unquoted `identifier`s may consist of latin letters a-z in any lettercase, digits 0-9, dollar, underscore, and Unicode extended characters in the range U+0080 to U+FFFF. `Identifier`s can start with any character that is legal in an `identifier`, including a digit. However, an unquoted `identifier` cannot consist entirely of digits because that would make it indistinguishable from a number. MySQL’s support for `identifier`s that begin with a number is somewhat unusual among database systems. If you use such an identifier, take particular care if it contains an \'E\' or \'e\' because those characters can lead to ambiguous expressions. For example, the expression 23e + 14 (with spaces surrounding the \'+\' sign) means column 23e plus the number 14, but what about 23e+14? Does it mean the same thing, or is it a number in scientific notation? `Identifier`s can be "quoted" (delimited) within backtick characters (\'`\'), which permits use of any character except a NUL byte or Unicode supplementary characters (U+10000 and up): "string \\"string\\" string" "string \\\\"string\\\\" string" \'string \\\'string\\\' string\' \'string \\\\\'string\\\\\' string\' `string string` `string `string` string`'; preg_match_all($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