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(`\[Full GC.*\)\)\s(?<FullGC1>[^KMG]*)(K|M|G)-\>(?<FullGC2>[^KMG]*)(K|M|G)\((?<FullGC3>[^KMG]*)`) var str = `28820.220: [Full GC (System.gc()) 8832K->8624K(37888K), 0.0261704 secs] 29372.500: [GC (Allocation Failure) 23984K->8816K(37888K), 0.0013546 secs] 29932.500: [GC (Allocation Failure) 24176K->8808K(37888K), 0.0017082 secs] 30492.500: [GC (Allocation Failure) 24168K->8960K(37888K), 0.0017122 secs] 31047.500: [GC (Allocation Failure) 24320K->8944K(37888K), 0.0020634 secs] 31602.500: [GC (Allocation Failure) 24304K->8992K(37888K), 0.0017542 secs] 32157.500: [GC (Allocation Failure) 24352K->8968K(37888K), 0.0018971 secs] 32420.247: [GC (System.gc()) 16160K->8944K(37888K), 0.0012816 secs] 32420.248: [Full GC (System.gc()) 8944K->8624K(37888K), 0.0205035 secs]` 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/