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

/
/
mg

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?m)^([a-zA-Z]\w+-[a-zA-Z]\w+-[a-zA-Z]\w+\.[a-zA-Z]\w+(?:-\w+)?\.v\d+(?:\.\d+\.\d+)?(?:(?:-rc|-alpha)(?:\.\d+)?)?)|(at\d{1,4}(?:\.\d{1,4})?)$`) var str = `openEHR-EHR-EVALUATION.diagnosis.v1 openEHR-EHR-COMPOSITION.report.v1 openEHR-EHR-COMPOSITION.report-procedure.v1 openEHR-EHR-COMPOSITION.care_plan.v0 openEHR-DEMOGRAPHIC-PERSON.person.v1 openEHR-EHR-OBSERVATION.test.v0 openEHR-EHR-OBSERVATION.test.v0.0.20 openEHR-EHR-OBSERVATION.test-extended.v1.0.20 openEHR-EHR-OBSERVATION.test-extended.v1.0.20-rc.1 openEHR-EHR-OBSERVATION.test-extended.v1.0.20-rc openEHR-EHR-OBSERVATION.second_test.v1.3.5-rc.3 openEHR-EHR-OBSERVATION.second_test-extended.v1.3.5-alpha openEHR-EHR-OBSERVATION.second_test-extended.v1.0.20 ISO-ISO13606-ENTRY.test.v0.1.9 br.ms::openEHR-EHR-OBSERVATION.haematology_result.v1.0.0 br.ms::openEHR-EHR-OBSERVATION.haematology_result.v1.2.15-alpha.45 br.ms::openEHR-EHR-OBSERVATION.haematology_result.v3.22.125-rc.7 org.openehr::openEHR-EHR-OBSERVATION.haematology.v1.2.0 uk.org.primary_care::openEHR-EHR-OBSERVATION.haematology_result.v1.2.15 at0003 at0003.190 at0000 at0.1 at0.123 at0.12345 at1234 at0000 id1.1 id1.77 ======================== openEHR-EHR-OBSERVATION.test-extended.v1.20-rc.1 openEHR-EHR-OBSERVATION.test-extended.v1.20-rc ISO-ISO-13606-ENTRY.test.v0.1.9 openEHR-EHR-OBSERVATION.v0.2 openEHR--OBSERVATION.v0.2 openEHR-EHR-EVALUATION.2steps.v1 openEHR-EHR-EVALUATION.diagnosis openEHR-EHR-EVALUATION.diagnosis.1 openEHR-EHR-EVALUATION.diagnosis.v openEHR-EHR-EVALUATION.diagnosis.v00 openEHR-EHR-EVALUATION.diagnosis.v0.00.00 at0.12345 at0.12.345 ac0001 at0001.at0001.at0001` 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/