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

// include the latest version of the regex crate in your Cargo.toml extern crate regex; use regex::Regex; fn main() { let regex = Regex::new(r"(?m)^ *[^\s]+( +[^\s]+)*$").unwrap(); let string = "# UFIS : User-Friendly and Instant Installer System # Each comment starts with '#' and ends with a new line. # Each statement is written in one line. # Commands' and built-in variables' names are always uppercase. # A custom variable name must have at least one lowercase character and must begin with a letter or the underscore (_). LET APP_NAME = \"MyApp\" LET APP_VERSION = \"1.0.0\" LET a = MATERIAL \"folderx/\" a -= \"test.exe\" a -= \"main.exe\" a += MATERIAL \"folderz/\" a += MATERIAL \"README.md\" LET b = MATERIAL \"folderx/test.exe\" LET c = MATERIAL \"folderx/main.exe\" IF INSTALLING LET iAcceptLicense = INPUT CHECKBOX \"Accept [license](https://myapp.com/license)\" MANDATORY IF iAcceptLicense == FALSE QUIT ENDIF LET iLanguage = INPUT CHOICES \"Vietnamese\" OR \"English\" DEFAULT \"English\" MANDATORY LET INSTALL_DIR = INPUT DIRECTORY \"Installation directory\" POSTFIX \"/${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 "; // result will be an iterator over tuples containing the start and end indices for each match in the string let result = regex.captures_iter(string); for mat in result { println!("{:?}", mat); } }

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 Rust, please visit: https://docs.rs/regex/latest/regex/