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

~
~
gx

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 = " \"[^\"\\\\]*(?s:\\\\.[^\"\\\\]*)*+\"\n" + " (*SKIP)(*F)\n" + "|\n" + " /\n" + " (?:\n" + " / .*\n" + " |\n" + " \\* [^*]* (?: \\*+(?!/) [^*]* )*+ (?:\\*/)?\n" + " )"; final String string = "/* toto****to ****/ /****/ \n" + "char * foo = \"//don't\\\" // remove\" \" // really please don't\"; // But remove this ha ha! // along with this!\n\n" + "char *bad_regex_strategy = \"\\\"good luck\\\" // \\\"counting the \\\"quotes\\\"\" \"//\\\"//\"; // \\\"ha\"\"\" \\\" \" \\\" ha ha\\\" ha /// \"\\;\"ha'\n" + "/*\n" + "and then imagine a copy of that entire line commented out on the next line of source.\n" + "I'd question the entire task and see if there isn't a C source manipulation library you should be using instead. ?\n" + " BaseZen 2 hours ago Is it? So when I have the choise between doing this by regex or final state machine, u recommend the FSM, right?\n" + " :/ ? user3457394 2 hours ago"; final Pattern pattern = Pattern.compile(regex, Pattern.COMMENTS); 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