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)^(?!^[0-9])(?![0-9][AZ])(?![AZ0-9*]*\*\*)(?![AZ0-9*]*\*[AZ])((?=[AZ0-9]{6})|(?=[AZ0-9*]*\*))(?![AZ0-9*]*[0-9][A-Z])[AZ0-9*]{1,6}$`) var str = `^(?![0-9])(?![0-9][AZ])(?![AZ0-9*]*\*\*)(?![AZ0-9*]*\*[AZ0])(?=[AZ0-9*]*\*)(?![AZ0-9*]*[0-9][A-Z])[AZ0-9*]{1,6}$ Broken down: ^(?![0-9]) (?![0-9][AZ]) (?![AZ0-9*]*\*\*) (?![AZ0-9*]*\*[AZ0]) (?=[AZ0-9*]*\*) (?![AZ0-9*]*[0-9][A-Z]) [AZ0-9*]{1,6}$ Check these for patterns Following would be valid * *1 *1* *12345 A* A*2 A*2* A1*3 A1*3* A12*4 A*2 A*23 A*234 A*2345 A12*45 A1234* A*2345 A12*4* A*23*5 A123*5 *12345 *1234* *1*3*5 *12*4* *1*3*5 *123*5 A12345 Examples of invalid entries: <Any ** entry> - <Any * A-Z character> - <Any value longer than 6> A1 A12 A123 A1234 *A1234 B* B1* BA*45 B*2345 ** *1A *1A1* *A2345 *123456 1234* A **12 *1** *1*3** *12** *1*3*56 *123** *12*45* A*23456` 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/