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

/
/
g

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`((([a-z]\[[^\]]+\])(.{1}))?(\s*\=\>\s*)((([a-z]\[[^\]]+\])|([a-z].))(.{1})([A-Z]?)))?(\s*\/\/.*)?`) var str = `// Алгоритм умножения. Формат ленты: [*]1111#111=* // Множество: Q; Начальное значение: q[0]; Конечное значение: q*; // Символ пустой ячейки: _; Символ перехода влево: L; Символ перехода вправо: R q[0]1 => q[0]1R //2312312323 q[0]# => q[1]#R q[0]* => q[0]*R q[1]1 => q[2]aR q[2]1 => q[2]1L q[2]# => q[3]#L q[2]= => q[2]=L q[2]a => q[2]aL q[3]1 => q[4]aR q[3]a => q[3]aL q[3]* => q[6]*R q[4]1 => q[4]1R q[4]# => q[4]#R q[4]= => q[4]=R q[4]a => q[4]aR q[4]* => q[5]1R q[5]_ => q[2]*L q[6]# => q[7]#R q[6]a => q[6]1R q[7]1 => q[2]aR q[7]= => q[8]=L q[7]a => q[7]aR q[8]# => q*# q[8]a => q[8]1L` 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/