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

`
`
g

Test String

Code Generator

Language

Generated Code

const regex = new RegExp('\\[((?P<serial>\\d{14}){0,1}[\\.\\w]*-(?P<pccode>[\\dA-Z]{8}))\\] +', 'g') const str = `2017-06-15 06:05:25*6 --- ERROR "?? ?.?.?. ??? ????? ????????"--- FieldName:AFM, OldValue:, NewValue:125433937 2017-06-15 06:05:25*6 [01102409405015-02CB3A00] setData ---- ESoftOneError: ?? ?.?.?. ??? ????? ???????? ***** 2017-06-15 06:05:25*6 [01102409405015-02CB3A00] getData ---- EDatabaseError: [42S22] [Microsoft][ODBC Driver 11 for SQL Server][SQL Server]Invalid column name 'false'. (207) [42S22] [Microsoft][ODBC Driver 11 for SQL Server][SQL Server]Invalid column name 'false'. (207) [42S22] [Microsoft][ODBC Driver 11 for SQL Server][SQL Server]Invalid column name 'false'. (207) 2017-06-15 06:05:46*3 [01100279451010-0D6626F0] calculate ---- Time: 4922 ms QCount: 29 QTime: 4624 DataIn: 1990 DataOut: 2576 [37 Trs - 224 MB - 18 %] 2017-06-15 06:05:51*3 [01100279451010-0D6626F0] setData ---- Time: 3437 ms QCount: 62 QTime: 265 DataIn: 1054 DataOut: 30 2017-06-15 06:06:14*5 [01102396363715-0839E1A0] Report (customer) ---- Time: 719 ms QCount: 1 QTime: 703 [176 Trs - 161 MB - 11 %] 2017-06-15 09:35:00*1 [01102342340813-86ED1F51] ******EXCEPTION ProcessPacket disp_ExecuteSQL EDatabaseError: [42000] [Microsoft][SQL Server Native Client 11.0][SQL Server]Incorrect syntax near 'SAMSUNG'. (102) [42000] [Microsoft][SQL Server Native Client 11.0][SQL Server]The identifier that starts with '</productDesc> <svcLevel>EDX0W</svcLevel> <svcLevelDesc>Express ; Customer requested day service</svcLevelDesc> <' is too long. Maximum length is 128. (103) 2017-06-14 08:42:49*2 [01102455824916-C29C87D0] ******EXCEPTION ProcessPacket disp_GetSQLResults EDatabaseError: [42S22] [Microsoft][ODBC Driver 11 for SQL Server][SQL Server]Invalid column name 'FIDNOC'. (207) [UPDATE ML SET ML.FINALDATE = CONVERT(VARCHAR,DATEADD(DD,M.CCCLOTDURATION,FD.TRNDATE),103) FROM FINDOC AS FD INNER JOIN MTRLINES AS FDL ON FDL.FINDOC = FD.FINDOC INNER JOIN MTRL AS M ON M.MTRL = FDL.MTRL AND M.CCCLOTDURATION IS NOT NULL INNER JOIN MTRLOT AS ML ON ML.MTRL = M.MTRL AND ML.MT] [13100 Trs - 464 MB - 5 %]`; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; while ((m = regex.exec(str)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === regex.lastIndex) { regex.lastIndex++; } // The result can be accessed through the `m`-variable. m.forEach((match, groupIndex) => { console.log(`Found match, group ${groupIndex}: ${match}`); }); }

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 JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions