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

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"^ *[^\s]+( +[^\s]+)*$"; string input = @"# UFIS : User-Friendly and Instant Installer System # Each comment starts with '#' and ends with a new line. # Each statement is written in one line. # Commands' and built-in variables' names are always uppercase. # A custom variable name must have at least one lowercase character and must begin with a letter or the underscore (_). LET APP_NAME = ""MyApp"" LET APP_VERSION = ""1.0.0"" LET a = MATERIAL ""folderx/"" a -= ""test.exe"" a -= ""main.exe"" a += MATERIAL ""folderz/"" a += MATERIAL ""README.md"" LET b = MATERIAL ""folderx/test.exe"" LET c = MATERIAL ""folderx/main.exe"" IF INSTALLING LET iAcceptLicense = INPUT CHECKBOX ""Accept [license](https://myapp.com/license)"" MANDATORY IF iAcceptLicense == FALSE QUIT ENDIF LET iLanguage = INPUT CHOICES ""Vietnamese"" OR ""English"" DEFAULT ""English"" MANDATORY LET INSTALL_DIR = INPUT DIRECTORY ""Installation directory"" POSTFIX ""/${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 "; RegexOptions options = RegexOptions.Multiline; 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