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

/
/
gm

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 = "(((?# FIRST TYPE OF ARGS\\\n" + ")(?#start arg)(\"|'|`)(?#\\\n" + ")(?#arg)(?<arg>(?# whole repeat pattern)((?!\\3)(?(?!\\\\).|..))*)(?#\\\n" + ")(?#end arg)\\3(?#\\\n" + "))|((?# SECOND TYPE OF ARGS\\\n" + ")(?#start arg)(^|\\s+)(?#\\\n" + ")(?#arg)(?<arg_>(?#whole repeat pattern)((?!\\s|$)(?(?!\\\\).|..))+)(?#\\\n" + ")))(?#\\\n" + "skipping trailing whitespaces)(\\s|^|$)*(?=(\\s|^|$|\"|'|`))"; final String string = " arg0\\ \\ \\\\ \"arg1\\\"\\\"\" \"arg2\\\"\\\\\"\"arg3 \\\"\" 'arg4\"arg4\"' arg5 arg6 \n\n" + " space_bef_and_aft_even_arg0 arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8 arg9 \n" + " space_bef_and_aft_odd__arg0 arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8 \n" + "space_aft_even__________arg0 arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8 arg9 \n" + "space_aft_odd___________arg0 arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8 \n" + " space_bef_even_________arg0 arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8 arg9\n" + " space_bef_odd__________arg0 arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8\n" + "nospace_even____________arg0 arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8 arg9\n" + "nospace_odd_____________arg0 arg1 arg2 arg3 arg4 arg5 arg6 arg7 arg8\n\n" + " multispace______________arg0 arg1 arg2 arg3 arg4 \n\n\n" + " pbm0 pbm1 pbm2 \n" + "\"pbm0 pbm0\" pbm1 \n" + "\"pbm0 pbm0\" pbm1 \n\n" + " C:\\ProgramData\\Anaconda3\\python.exe C:\\ProgramData\\Anaconda3\\cwp.py C:\\ProgramData\\Anaconda3 C:\\ProgramData\\Anaconda3\\python.exe C:\\ProgramData\\Anaconda3\\Scripts\\jupyter-notebook-script.py \"%USERPROFILE%/\" \n\n" + " (?(?=\\2)(?(?=($|^))true|false)|false) . \n\n\n\n\n" + "(?:(?(?!\\3|\\\\).|(?=\\\\)..))*\n\n" + "((?!\\s|$)(?(?!\\\\).|..))*)"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); 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