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

/
/
gm

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?m)(?:\"(?:(?<=\"(?=[^\n]))[^\n]+?(?=(?<!\\))(?=\"))?\")|(\B'(?:(?<='(?=[^\n]))[^\n]+?(?=(?<!\\))(?='))?')`) var str = ` 1. Valid double-quoted strings: - "Hello" - "This is a test" - "123" - "Special characters: @#$%^&*()_+" - "Escape sequence: \n" 2. Valid double-quoted strings with additional characters or variables: - " test aaaaa \" " + asdf - " test " + ( "aaaaa" ) + gdf - " test \" " + \`" aaaa " + dfg - " test ' aaaaa \" " + dfg - "" 3. Valid double-quoted strings with special characters: - "sas''as\"a1\'2 ! -_?:sa" - "''" - "\abnb\ajhgf\crt098& \"'" 4. Invalid double-quoted strings: - " test " + ( "aaaaa" ) \" saf - "\\ + \* test " \$ \. dsdfs - (\" test \" " + " aaaa " sfgd - ' test ' + aas ( "aaaaa" ) + '\ sd - '\\ + \* test ' \$ \. trace - (' test ' as ' + ' aaaa ' - '""' - '"sas' - 'ads' - 'asdasd\"asdsa' - "klkl"klkl - "asa\'sasa\\" - \'\\\' - "hhhh"klkl" - 'jkjkjk'klklk' - '\"\\\"' - '' - '\"asa\'sasa\\\"' - "sasasasa\\\\\\" 1. Valid single-quoted strings: - 'Hello' - 'This is a test' - '123' - 'Special characters: @#$%^&*()_+' - 'Escape sequence: \n' 2. Valid single-quoted strings with additional characters or variables: - ' test aaaaa \' ' + asdf - ' test ' + ( 'aaaaa' ) + gdf - ' test \' ' + ' aaaa' + dfg - ' test " aaaaa \' ' + dfg - '' 3. Valid single-quoted strings with special characters: - 'sas""as\'a1\"2 ! -_?:sa' - '""' - '\abnb\ajhgf\crt098& \'""' 4. Invalid single-quoted strings: - ' test ' + ( 'aaaaa' ) \' saf - '\\ + \* test ' \$ \. dsdfs - (\' test \' + ' aaaa ' sfgd - " test \" " + " aaaa " sfgd - ' test ' + aas ( 'aaaaa' ) + '\ sd - '\\ + \* test ' \$ \. trace - (' test ' as ' + ' aaaa ' - "''" - 'sas" - "ads' - 'asdasd\'asdsa' - "klkl"klkl - "asa\'sasa\\" - \'\\\' - 'hhhh"klkl\'\ - \'jkjkjk"klklk' - "\'\\\'" - '' - '\"asa\'sasa\\\"' - 'sasasasa\\\\\\' ` 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/