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"""
"""
g

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`<a.*href.?=.?["'](?:\b\w+://)?([\w-]+(?:\.[\w-]+)+)[/:?]?.*?["'].*?>?(?:</)?.?>`) var str = `<a href="http://stepic.org/courses"> <a href='https://stepic.org'> <a href='http://neerc.ifmo.ru:1345'> <a href="ftp://mail.ru/distib" > <a href="ya.ru"> <a href="www.ya.ru"> <a href="../skip_relative_links"> <a target="blank" href='http://sas-_0123d.ifmo.ru:1345'> <a href='http://neerc.ifmo.ru:1345'> <a href="../some_path/index.html"> <a href="https://www.ya.ru"> <a href="ftp://mail.ru/distib" > <a href="bya.ru"> <a href="http://www.ya.ru"> <a href="www.kya.ru"> <a href="../skip_relative_links"> <a href="http://stepic.org/courses"> <a class = "hello" href= "http://ftepic.org/courses" id="dfdf"> <p class = "hello" href= "http://dtepic.org/courses"> <a class = "hello" href = "http://a.b.vc.ttepic.org/courses"> <a href='https://stepic.org'> <a href='http://neerc.ifmo.ru:1345' > <a href = "ftp://mail.ru/distib" > <a href= "ya.ru"> <a href ="www.ya.ru"> <a href="../skip_relative_links"> <link rel="image_src" href="https://examaple.org/files/6a2/72d/e09/6a272de0944f447fb5972c44cc02f795.png" /> <a href="http://www.gtu.edu.ge/index_e.htm" target="_top">Georgian Technical University</a> <a href="http://stepic-2.org/courses"> <a href="ftp://www.mya-2.ru"> <a href='https://stepic-2.org'> <a link href='http://neerc.ifmo-2.ru:1345'> <a title=test download="http://test.com"; href="test.com" class="my test" style=> <a title=test class="my test" href= "test1.com:8080/test/path?get=http://test2.ru/?true"; rel="nofollow" style=> <a title=test meta="whatever http://test1.com"; href = "test.com?get=http://test2.ru/?true"; class="my test" style= > <a target="blank" href='http://sasd.ifmo-2.ru:1345'> <a href='http://neerc.ifmo-2.ru:1345'> <a href="../some_path/index-2.html"> <a href="https://www.ya-2.ru"> <a href="ftp://mail-2.ru/distib" > <a href="bya-2.ru"> <a href="http://www.ya-2.ru"> <a href="www.kya-2.ru" > <a href="../skip_relative_links-2"> <a href="http://stepic-2.org/courses"> <a class = "hello-2" href= "http://ftepic-2.org/courses" id="dfdf"> <p class = "hello-2" href= "http://dtepic-2.org/courses"> <a class = "hello-2" href = "http://a.b.vc.ttepic-2.org/courses"> <a href='https://stepic-2.org'> <a href='http://neerc.ifmo-2.ru:1345' > <a href = "ftp://mail-2.ru/distib" > <a href= "ya-2.ru"> <a href ="www.ya-2.ru"> <a href="../skip_relative_links"> <link rel="image_src" href="https://examaple.org/files/6a2/72d/e09/6a272de0944f447fb5972c44cc02f795.png" /> <a href="http://www.gtu.edu-2.ge/index_e.htm" target="_top">Georgian Technical University</a> <a class-8 = "hello-2" href= "http://zzz.last.test-1.stepic.org/courses" id="dfdf"> <a class-4-4 = "hello-2-raz" href = "http://zzz.last.test-2.stepic.org/courses" > <a href ="https://stepic.org/media/attachments/lesson/24471/02">` 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/