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

/
/
gm

Test String

Code Generator

Language

Generated Code

use strict; my $str = '# UFIS : User-Friendly and Instant Installer System # Each comment starts with \'#\' and ends with a new line. # Each statement is written in one line. # Commands\' and built-in variables\' names are always uppercase. # A custom variable name must have at least one lowercase character and must begin with a letter or the underscore (_). LET APP_NAME = "MyApp" LET APP_VERSION = "1.0.0" LET a = MATERIAL "folderx/" a -= "test.exe" a -= "main.exe" a += MATERIAL "folderz/" a += MATERIAL "README.md" LET b = MATERIAL "folderx/test.exe" LET c = MATERIAL "folderx/main.exe" IF INSTALLING LET iAcceptLicense = INPUT CHECKBOX "Accept [license](https://myapp.com/license)" MANDATORY IF iAcceptLicense == FALSE QUIT ENDIF LET iLanguage = INPUT CHOICES "Vietnamese" OR "English" DEFAULT "English" MANDATORY LET INSTALL_DIR = INPUT DIRECTORY "Installation directory" POSTFIX "/${APP_NAME}" DEFAULT PROGRAM_FILES LET iInstallTest = INPUT CHECKBOX "Install test.exe" DEFAULT FALSE LET iCreateDesktopShortcut = INPUT CHECKBOX "Create desktop shortcut" DEFAULT TRUE LET iLaunchAtStartup = INPUT CHECKBOX "Launch program at startup" DEFAULT TRUE INSTALL a AND c TO INSTALL_DIR # the same as "${INSTALL_DIR}" IF iInstallTest == TRUE INSTALL b TO INSTALL_DIR AS "test_program.exe" ENDIF IF iCreateDesktopShortcut == TRUE CREATE SHORTCUT FOR c IN DESKTOP_ALL_USERS ENDIF IF iLaunchAtStartup == TRUE RUN c AT STARTUP ENDIF WORK registry_work CREATE REGSZ "HKEY_LOCAL_MACHINE/Software/${APP_NAME}" VALUE "1" ENDWORK CPP #include <iostream> void entry() { std::cout << "Not very intelligent"; } ENDCPP CALL entry ELIF RUNNING RUN c ELSE # UNINSTALLING UNDO ALL EXCEPT registry_work ENDIF '; my $regex = qr/^ *[^\s]+( +[^\s]+)*$/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