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
Processing...

Test String

Code Generator

Language

Generated Code

use strict; my $str = ' kex_algorithms: (8) curve25519-sha256@libssh.org ecdh-sha2-nistp256 ecdh-sha2-nistp384 ecdh-sha2-nistp521 diffie-hellman-group-exchange-sha256 diffie-hellman-group-exchange-sha1 diffie-hellman-group14-sha1 diffie-hellman-group1-sha1 server_host_key_algorithms: (4) ssh-rsa ssh-dss ecdsa-sha2-nistp256 ssh-ed25519 encryption_algorithms: (14) aes128-ctr aes192-ctr aes256-ctr arcfour256 arcfour128 chacha20-poly1305@openssh.com aes128-cbc 3des-cbc blowfish-cbc cast128-cbc aes192-cbc aes256-cbc arcfour rijndael-cbc@lysator.liu.se mac_algorithms: (19) hmac-md5-etm@openssh.com hmac-sha1-etm@openssh.com umac-64-etm@openssh.com umac-128-etm@openssh.com hmac-sha2-256-etm@openssh.com hmac-sha2-512-etm@openssh.com hmac-ripemd160-etm@openssh.com hmac-sha1-96-etm@openssh.com hmac-md5-96-etm@openssh.com hmac-md5 hmac-sha1 umac-64@openssh.com umac-128@openssh.com hmac-sha2-256 hmac-sha2-512 hmac-ripemd160 hmac-ripemd160@openssh.com hmac-sha1-96 hmac-md5-96 compression_algorithms: (2) none zlib@openssh.com"'; my $regex = qr/(?<test>^\s+\K(umac|hmac)[\w\-\.@]+)/mp; if ( $str =~ /$regex/g ) { print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n"; # print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n"; # print "Capture Group 2 is $2 ... and so on\n"; } # ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p' # Named capture groups can be called via $+{name}

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 Perl, please visit: http://perldoc.perl.org/perlre.html