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

r"
"
gm

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?m)\b(?<=\w)\s{20}`) var str = `Ateles_geoffroyi GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT Ateles_hybridus GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT Ateles_fusciceps GATGAGTGTGGCAAGGCCCAAGCGGAAGTGC?????????? Ateles_chamek GATGAGTGTGGCAAGGCCCA????????????????????? Ateles_paniscus ????????????????????????????????????????? Brachyteles_arachnoides GATGAGTGTGGCAAGGCCCAAGCGGAAGT???????????? Brachyteles_hypoxanthus GATGAGTGTGGCAAG?????????????????????????? Lagothrix_cana GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT Lagothrix_lagotricha GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT Alouatta_belzebul ????????????????????????????????????????? Alouatta_caraya ????????????????????????????????????????? Alouatta_sara GATGAATGTGGCAAGGCCCAAGCAGAAGTGCCG--GTTGCT Alouatta_palliata GATGAATGTGGCAAGGCCCAAGCAGAAGTGCCG--GTTGCT Callicebus_brunneus ????????????????????????????????????????? Callicebus_moloch GATGAGTGTGGCAAGGCCCAAGCAGAAGTGCCG--G????? Callicebus_cupreus GATGAGTGTGGCAAGGCCCAAGCAGAAGTGCCG--GTTGCT Callicebus_caligatus GATGAGTGTGGCAAGGCCCAAGCAGAAGTGCCG--GTTGCT Callicebus_donacophilus GATGAGTGTGGCAAGGCCCAAGCAGAAGTGCCG--GTTGCT Callicebus_coimbrai GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT Callicebus_personatus GATGAGTGTGGCAAGGCCCAAGCGGAA?????????????? Callicebus_nigrifrons GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT Cacajao_melanocephalus GATGAGTGTGGCAAAGCCCA????????????????????? Cacajao_calvus GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT Chiropotes_israelita GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT Chiropotes_satanas_chiro ????????????????????????????????????????? Pithecia_irrorata GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--G????? Pithecia_pithecia GATGAGTGTGGCAAGGCCCAAGCGGAAGTGCCG--GTTGCT Tarsius_bancanus ????????????????????????????????????????? Tarsius_syrichta ????????????????????????????????????????? Lepilemur_ankaranensis AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Lepilemur_septentrionali AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Lepilemur_dorsalis AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Lepilemur_ruficaudatus AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Lepilemur_jamesi AACGAGTGTGGCAAGGCCCAGG??????????????????? Microcebus_murinus_subsp AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Microcebus_murinus_subsp ????????????????????????????????????????? Mirza_zaza AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Cheirogaleus_medius ????????????????????????????????????????? Propithecus_verreauxi_co ????????????????????????????????????????? Propithecus_verreauxi AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Propithecus_tattersalli AACGAGTGTGGCAAGGCCCAGGCTGAAGTTCCG--GTTGCT Propithecus_diadema AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Propithecus_edwardsi AACGAGTGTGGCAAGGCCCAGGCG????????????????? Avahi_laniger AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Eulemur_rufus AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Eulemur_collaris AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Eulemur_fulvus AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Eulemur_albifrons AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Eulemur_sanfordi AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Eulemur_mongoz AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Eulemur_macaco AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Eulemur_macaco_flavifron AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Eulemur_coronatus AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Eulemur_rubriventer AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Hapalemur_occidentalis AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Hapalemur_griseus AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Lemur_catta AACGAGTGTGGCAAGGCCCAGGCGGAAGTTCCG--GTTGCT Varecia_variegata_varieg AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Varecia_variegata_rubra AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Daubentonia_madagascarie ????????????????????????????????????????? Nycticebus_bengalensis AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Nycticebus_coucang AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Nycticebus_pygmaeus AACGAGTATGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Loris_tardigradus AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Arctocebus_calabarensis AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Perodicticus_potto AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Otolemur_garnetti AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Otolemur_crassicaudatus AACGAGTGTGGCAAGGCCCAGGCAGAAGTTCCG--GTTGCT Galago_moholi ????????????????????????????????????????? Galago_senegalensis ????????????????????????????????????????? Galago_thomasi AACGAGTGTGGCAAGGCCCAGGCG????????????????? Galeopterus_variegatus GATGAGTGTGGCAAGGCCCAAGCAGAAGTTCCG--G????? Cynocephalus_volans GATGAGTGTGGCAAGGCCCAAGCAGAAGTCCCG--GTTGCT Tupaia_glis ????????????????????????????????????????? Tupaia_minor ????????????????????????????????????????? rabbit_rabbit_rabbit ????????????????????????????????????????? ` 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/