Regular Expressions 101

Save & Share

  • Regex Version: ver. 13
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

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

r"
"
gx

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`# Parse table of SWPC event data (?P<event>\d{4}) \s+ (?P<multi_event_flag>\+)? \s+ (?P<time_start_flag>\w)? (?P<time_start>\d{4}) \s+ (?P<time_peak_flag>\w)? (?: (?P<time_peak>\d{4})| /{4} ) \s+ (?P<time_end_flag>\w)? (?P<time_end>\d{4}) \s+ (?P<observatory>\w{3}) \s+ (?P<quality>\w) \s+ (?P<type>\w{3}) \s+ (?: (?P<location> (?P<lat_hg>\w\d{2}) (?P<long_hg>\w\d{2}) )| (?P<frequency_range> (?P<from>\w+) \- (?P<to>\w+) )| (?P<frequency> (\d{3}) )| (?P<no_freq> (/{4}) ) ) \s+ (?P<particulars_1>[\w/\.\+]+) \s+ (?: (?P<particulars_2> (?:\d\.\d\w[\-\+]\d{2})? )| (?P<particulars_3>\w{3}?)| () ) \s+ (?: (?P<regnum>\d{4})| () ) \n`) var str = `:Product: 20050316events.txt :Created: 2005 Mar 17 1802 UT :Date: 2005 03 16 # Prepared by the U.S. Dept. of Commerce, NOAA, Space Environment Center. # Please send comments and suggestions to SEC.Webmaster@noaa.gov # # Missing data: //// # Updated every 30 minutes. # Edited Events for 2005 Mar 16 # #Event Begin Max End Obs Q Type Loc/Frq Particulars Reg# #------------------------------------------------------------------------------- 1590 0318 0318 0318 LEA G RBR 245 51 1620 + 0348 //// 1635 COM C RSP 30-80 CTM/1 1600 + 0408 0410 0412 LEA G RBR 245 210 1730 + 0422 1214 1511 COM G RNS 245 160 1610 0522 0528 0532 G10 5 XRA 1-8A B4.2 1.9E-04 1630 0741 0744 0748 G10 5 XRA 1-8A B1.9 7.3E-05 1630 0741 //// 0743 SVI C RSP 025-089 III/1 1640 1052 //// 1053 SVI U RSP 025-046 III/1 1650 1125 1125 1125 SVI G RBR 245 85 1650 1125 1125 1125 SVI G RBR 410 46 1660 1150 //// 1150 SVI C RSP 025-041 III/1 1670 + 1205 1208 1210 G12 5 XRA 1-8A B3.5 8.1E-05 0742 1670 1206 1206 1209 SAG G RBR 245 100 0742 1670 1207 1207 1207 SAG G RBR 410 56 0742 1670 1209 1210 1210 G12 5 XFL S02W48 3.0E+02 6.5E+02 0742 1670 1210 //// 2228 SAG C RSP 110-180 CTM/1 0742 1680 + 1217 1221 1223 G12 5 XRA 1-8A B5.1 1.4E-04 0742 1680 + 1219 1219 1219 SVI G RBR 410 310 0742 1680 1221 1222 1223 G12 5 XFL S03W50 7.5E+02 2.3E+03 0742 1690 + 1242 1245 1247 G12 5 XRA 1-8A B3.1 7.7E-05 0742 1690 1246 1246 1247 G12 5 XFL S07W48 4.3E+02 9.1E+02 0742 1700 + 1306 //// 1306 SAG C RSP 030-053 III/1 1710 + 1318 1322 1332 G12 5 XRA 1-8A B3.0 2.3E-04 0742 1710 1322 1327 1331 G12 5 XFL S07W53 2.3E+02 4.6E+02 0742 1720 + 1339 //// 1339 SVI C RSP 025-034 III/1 1750 1450 //// 1451 SVI C RSP 025-180 III/1 1760 + 1542 1547 1554 G12 5 XRA 1-8A B3.8 2.1E-04 0742 1760 + 1544 1544 1546 SAG G RBR 245 380 0742 1760 + 1544 //// 1545 SAG C RSP 030-180 III/1 0742 1760 1546 1550 1553 G12 5 XFL S07W54 4.8E+02 1.0E+03 0742 1770 1633 //// 1634 SAG C RSP 030-050 III/1 1780 1755 //// 1756 SAG C RSP 030-053 III/1 1790 + 1851 //// 1851 PAL C RSP 025-085 III/1 1800 + 1947 1953 1959 G12 5 XRA 1-8A B5.9 3.3E-04 0742 1800 1952 1957 1957 G12 5 XFL S06W57 7.3E+02 1.8E+03 0742 1810 + 2029 2034 2036 G12 5 XRA 1-8A B5.3 1.6E-04 0742 1810 + 2030 //// 2032 CUL C RSP 20-350 III/2 0742 1810 B2033 2033 2035 G12 5 XFL S07W54 7.8E+02 2.0E+03 0742 1810 + 2035 2035 2035 PAL G RBR 245 110 0742 1810 2035 U2035 2035 PAL G RBR 410 63 0742 1820 + 2049 2053 2056 G12 5 XRA 1-8A B3.6 1.3E-04 0742 1820 2051 //// 2051 CUL C RSP 40-160 III/1 0742 1820 2053 2053 A2053 G12 5 XFL S02W55 1.8E+02 3.3E+02 0742 1830 + 2116 2116 2116 PAL G RBR 245 630 1830 + 2116 2116 2116 PAL G RBR 410 130 1830 2116 2116 2116 PAL G RBR 606 67 1830 2116 //// 2116 CUL C RSP 40-460 III/2 1840 + 2304 2314 2316 G12 5 XRA 1-8A B9.8 4.6E-04 0742 1840 2309 2313 2316 G12 5 XFL S07W56 2.0E+03 5.3E+03 0742 1840 2313 2313 2318 HOL 3 FLA S06W52 SF ERU 0742 1840 2313 //// 2315 PAL C RSP 025-180 V/1 0742 1840 + 2314 2314 2314 PAL G RBR 245 160 0742 1840 + 2314 2314 2314 PAL G RBR 410 1700 0742 1840 + 2314 //// 2315 CUL C RSP 18-500 III/3 0742 ` for i, match := range re.FindAllString(str, -1) { fmt.Println(match, "found at index", 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 Golang, please visit: https://golang.org/pkg/regexp/