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

/
/
gs

Test String

Code Generator

Language

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "type\\s([_A-Za-z]+)\\s*=\\s*(function|procedure)(.*?cdecl;)\\s*var(\\s[_A-Za-z]+):\\s*([_A-Za-z]+)\\s(external.*?;)"; final String string = "\n" + "// It's better to create the object with the right prototype from the start.\n" + "type TJS_SetPrototype = function (cx: PJSContext; var obj: PJSObject;\n" + " var proto: PJSObject):Boolean; cdecl;\n" + "var JS_SetPrototype: TJS_SetPrototype external SpiderMonkeyLib name 'SM_SetPrototype';\n\n\n" + "/// Write access an object's reserved slots\n" + "type TJS_SetReservedSlot = procedure (obj: PJSObject; index: uint32;\n" + " var v: jsval); cdecl;\n" + "var JS_SetReservedSlot: TJS_SetReservedSlot external SpiderMonkeyLib name 'SM_SetReservedSlot';\n"; final Pattern pattern = Pattern.compile(regex, Pattern.DOTALL); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(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 Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html