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

/
/
gx

Test String

Code Generator

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"(?<![^\{]\{)\{(?:(?:(?:[A-Za-z_]\w*|(?:[1-9]\d*|0|0[Oo]?[0-7]+|0[Xx][0-7]+|0[Bb][01]+)))?(?:\.[A-Za-z_]\w*|\[(?:(?:[1-9]\d*|0|0[Oo]?[0-7]+|0[Xx][0-7]+|0[Bb][01]+)|[^\]\}}\{{]+)\])*)?(?:\![rsa])?(?:\:(?:(?:.?[<>=\^])?[\x20+-]?\#?0?(?:[1-9]\d*|0|0[Oo]?[0-7]+|0[Xx][0-7]+|0[Bb][01]+)?,?(?:\.(?:[1-9]\d*|0|0[Oo]?[0-7]+|0[Xx][0-7]+|0[Bb][01]+))?[bcdEeFfGgnosXx%]?))?\}(?!\}[^\}])"; string input = @".. _formatexamples: Format examples ^^^^^^^^^^^^^^^ This section contains examples of the new format syntax and comparison with the old ``%``-formatting. In most of the cases the syntax is similar to the old ``%``-formatting, with the addition of the ``{}`` and with ``:`` used instead of ``%``. For example, ``'%03.2f'`` can be translated to ``'{:03.2f}'``. The new format syntax also supports new and different options, shown in the follow examples. Accessing arguments by position:: >>> '{0}, {1}, {2}'.format('a', 'b', 'c') 'a, b, c' >>> '{}, {}, {}'.format('a', 'b', 'c') # 2.7+ only 'a, b, c' >>> '{2}, {1}, {0}'.format('a', 'b', 'c') 'c, b, a' >>> '{2}, {1}, {0}'.format(*'abc') # unpacking argument sequence 'c, b, a' >>> '{0}{1}{0}'.format('abra', 'cad') # arguments' indices can be repeated 'abracadabra' Accessing arguments by name:: >>> 'Coordinates: {latitude}, {longitude}'.format(latitude='37.24N', longitude='-115.81W') 'Coordinates: 37.24N, -115.81W' >>> coord = {'latitude': '37.24N', 'longitude': '-115.81W'} >>> 'Coordinates: {latitude}, {longitude}'.format(**coord) 'Coordinates: 37.24N, -115.81W' Accessing arguments' attributes:: >>> c = 3-5j >>> ('The complex number {0} is formed from the real part {0.real} ' ... 'and the imaginary part {0.imag}.').format(c) 'The complex number (3-5j) is formed from the real part 3.0 and the imaginary part -5.0.' >>> class Point(object): ... def __init__(self, x, y): ... self.x, self.y = x, y ... def __str__(self): ... return 'Point({self.x}, {self.y})'.format(self=self) ... >>> str(Point(4, 2)) 'Point(4, 2)' Accessing arguments' items:: >>> coord = (3, 5) >>> 'X: {0[0]}; Y: {0[1]}'.format(coord) 'X: 3; Y: 5' Replacing ``%s`` and ``%r``:: >>> ""repr() shows quotes: {!r}; str() doesn't: {!s}"".format('test1', 'test2') ""repr() shows quotes: 'test1'; str() doesn't: test2"" Aligning the text and specifying a width:: >>> '{:<30}'.format('left aligned') 'left aligned ' >>> '{:>30}'.format('right aligned') ' right aligned' >>> '{:^30}'.format('centered') ' centered ' >>> '{:*^30}'.format('centered') # use '*' as a fill char '***********centered***********' Replacing ``%+f``, ``%-f``, and ``% f`` and specifying a sign:: >>> '{:+f}; {:+f}'.format(3.14, -3.14) # show it always '+3.140000; -3.140000' >>> '{: f}; {: f}'.format(3.14, -3.14) # show a space for positive numbers ' 3.140000; -3.140000' >>> '{:-f}; {:-f}'.format(3.14, -3.14) # show only the minus -- same as '{:f}; {:f}' '3.140000; -3.140000' Replacing ``%x`` and ``%o`` and converting the value to different bases:: >>> # format also supports binary numbers >>> ""int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}"".format(42) 'int: 42; hex: 2a; oct: 52; bin: 101010' >>> # with 0x, 0o, or 0b as prefix: >>> ""int: {0:d}; hex: {0:#x}; oct: {0:#o}; bin: {0:#b}"".format(42) 'int: 42; hex: 0x2a; oct: 0o52; bin: 0b101010' Using the comma as a thousands separator:: >>> '{:,}'.format(1234567890) '1,234,567,890' Expressing a percentage:: >>> points = 19.5 >>> total = 22 >>> 'Correct answers: {:.2%}'.format(points/total) 'Correct answers: 88.64%' Using type-specific formatting:: >>> import datetime >>> d = datetime.datetime(2010, 7, 4, 12, 15, 58) >>> '{:%Y-%m-%d %H:%M:%S}'.format(d) '2010-07-04 12:15:58' Nesting arguments and more complex examples:: >>> for align, text in zip('<^>', ['left', 'center', 'right']): ... '{0:{fill}{align}16}'.format(text, fill=align, align=align) ... 'left<<<<<<<<<<<<' '^^^^^center^^^^^' '>>>>>>>>>>>right' >>> >>> octets = [192, 168, 0, 1] >>> '{:02X}{:02X}{:02X}{:02X}'.format(*octets) 'C0A80001' >>> int(_, 16) 3232235521 >>> >>> width = 5 >>> for num in range(5,12): ... for base in 'dXob': ... print '{0:{width}{base}}'.format(num, base=base, width=width), ... print ... 5 5 5 101 6 6 6 110 7 7 7 111 8 8 10 1000 9 9 11 1001 10 A 12 1010 11 B 13 1011 "; RegexOptions options = RegexOptions.IgnorePatternWhitespace; foreach (Match m in Regex.Matches(input, pattern, options)) { Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index); } } }

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 C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx