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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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)US\s*(?:[2-9]\d{3}\/?\d{7}\s*A[129]|\d{7}\s*B[12])`) var str = `发明专利申请号 1-6 位顺序号或 2 位序列号 (01-28)+/6 位顺序号 1234 13/001234 发明专利临时申请号 60+/6 位顺序号或 61/+/6 位 顺序号 60/001234 61/000456 发明专利申请公布号 US+4 位年代+/7 位顺序号 +A1 无 US 2001/0001111 A1 发明专利申请再公布号 US+4 位年代+/7 位顺序号 +A2 无 US 2002/0042300 A2 发明专利申请公布的更 正号 US+4 位年代+/7 位顺序号 +A9 无 US 2002/0090260 A9 发明专利号（无专利申 请公布） 1-7 位顺序号或 US+1-7 位顺 序号+B1 123456 US 6198606 B1 发明专利号（有专利申 请公布） US+1-7 位顺序号+B2 无 US 6654321 B2 ` 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/