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(`^(?=[^P]*(?:ParNew|P.*ParNew|PSYoungGen|DefNew)).*?(?P<ParNew_before_1>\d+)K->(?P<ParNew_after_1>\d+)K\((?P<young_heap_size>\d+)K\), (?P<par_new_duration>\d+\.\d+) secs\] (?P<ParNew_before_2>\d+)K\->(?P<ParNew_after_2>\d+)K\((?P<total_heap_size>\d+)`) var str = `146372.273: [GC146372.274: [ParNew: 378633K->88155K(419456K), 0.0313803 secs] 9893391K->9602913K(12478080K), 0.0320299 secs] [Times: user=0.32 sys=0.01, real=0.03 secs] 2017-05-12T10:35:46.076+0000: 2.799: [GC2017-05-12T10:35:46.076+0000: 2.800: [ParNew: 409024K->51072K(460096K), 0.3273966 secs] 409024K->121051K(2046080K), 0.3275292 secs] [Times: user=0.31 sys=0.07, real=0.33 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/