Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "0?(?P<month>10|11|12|1|2|3|4|5|6|7|8|9)[—](?P<day>[1-2][0-9]|3[0-1]|[0]?[1-9])[—](?P<year>(19|20)\\d{2})[ ](?P<desc>.*?)[ ](?P<amount>[-]?[S]?\\d*\\.\\d+)"; final String string = "11—04—2022 ACH Deposit Square Inc 221104P2 126.42\n" + "11—07—2022 ACH Deposit Square Inc 221107P2 184.86\n" + "11—07—2022 ACH Deposit Square Inc 221107P2 225.67\n" + "11—09—2022 ACH Deposit Square Inc 221109P2 277.19\n" + "11—10—2022 ACH Deposit Square Inc 221110P2 306.31\n" + "11—14—2022 ACH Deposit Square Inc 221114P2 19.38\n" + "11—14—2022 ACH Deposit Square Inc 221111P2 126.42\n" + "11—14—2022 ACH Deposit Square Inc 221114P2 213.98\n" + "11—16—2022 ACH Deposit Square Inc 221116P2 175.02\n" + "11—17—2022 ACH Deposit Square Inc 221117P2 157.49\n" + "11—18—2022 ACH Deposit Square Inc 221118P2 308.4"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

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 Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html