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

r"
"
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 = "(([a-hKQNB]x)?(R[1-8]?[a-f]?x)?[KQNBR]?[abcdefgh]([1-8]{1}(?!=))(\\(ep\\))?((?<=[18])=[KQNBR])?\\+\\{,2\\}|0(-0){1,2})"; final String string = " <dt>e4</dt><dd>match</dd>\n" + " <dt>a8</dt><dd>match</dd>\n" + " <dt>g5</dt><dd>match</dd>\n" + " <dt>h7</dt><dd>match</dd>\n" + " <dt>a1</dt><dd>match</dd>\n" + " <dt>Kd2</dt><dd>match</dd>\n" + " <dt>Kg6</dt><dd>match</dd>\n" + " <dt>Qh4</dt><dd>match</dd>\n" + " <dt>Qe2</dt><dd>match</dd>\n" + " <dt>Qb7</dt><dd>match</dd>\n" + " <dt>Nf2</dt><dd>match</dd>\n" + " <dt>Nc6</dt><dd>match</dd>\n" + " <dt>Be4</dt><dd>match</dd>\n" + " <dt>Bf3</dt><dd>match</dd>\n" + " <dt>Bb2</dt><dd>match</dd>\n" + " <dt>Ra1</dt><dd>match</dd>\n" + " <dt>Rc3</dt><dd>match</dd>\n" + " <dt>Rh8</dt><dd>match</dd>\n" + " <dt>0-0</dt><dd>match</dd>\n" + " <dt>0-0-0</dt><dd>match</dd>\n" + " <dt>exd5</dt><dd>match</dd>\n" + " <dt>axb7</dt><dd>match</dd>\n" + " <dt>exd2</dt><dd>match</dd>\n" + " <dt>Bxc6</dt><dd>match</dd>\n" + " <dt>Bxa4</dt><dd>match</dd>\n" + " <dt>Qxe2</dt><dd>match</dd>\n" + " <dt>Qxb7</dt><dd>match</dd>\n" + " <dt>Nxf2</dt><dd>match</dd>\n" + " <dt>Nxb2</dt><dd>match</dd>\n" + " <dt>Bxb2</dt><dd>match</dd>\n" + " <dt>Rxh8</dt><dd>match</dd>\n" + " <dt>Rxc3</dt><dd>match</dd>\n" + " <dt>exd5(ep)</dt><dd>match</dd>\n" + " <dt>exd2(ep)</dt><dd>match</dd>\n" + " <dt>a1=Q</dt><dd>match</dd>\n" + " <dt>d1=Q</dt><dd>match</dd>\n" + " <dt>f8=Q</dt><dd>match</dd>\n" + " <dt>e8=Q</dt><dd>match</dd>\n" + " <dt>a1=N</dt><dd>match</dd>\n" + " <dt>b8=B</dt><dd>match</dd>\n" + " <dt>f1=R</dt><dd>match</dd>\n" + " <dt>d8=Q</dt><dd>match</dd>\n" + " <dt>bxc1=Q</dt><dd>match</dd>\n" + " <dt>exd1=Q</dt><dd>match</dd>\n" + " <dt>Raxc1</dt><dd>match</dd>\n" + " <dt>Rfxd2</dt><dd>match</dd>\n" + " <dt>R2xc1</dt><dd>match</dd>\n" + " <dt>R5xd2</dt><dd>match</dd>\n" + " <dt>Bxc6+</dt><dd>match</dd>\n" + " <dt>Rxh8+</dt><dd>match</dd>\n" + " <dt>Rh8+</dt><dd>match</dd>\n" + " <dt>Bxb2+</dt><dd>match</dd>\n" + " <dt>Rxc3++</dt><dd>match</dd>\n" + " <dt>Bxc6++</dt><dd>match</dd>\n" + " <dt>d8=Q++</dt><dd>match</dd>\n\n" + " <dt>2</dt><dd>no match</dd>\n" + " <dt>b</dt><dd>no match</dd>\n" + " <dt>i2</dt><dd>no match</dd>\n" + " <dt>a9</dt><dd>no match</dd>\n" + " <dt>5d</dt><dd>no match</dd>\n" + " <dt>K2</dt><dd>no match</dd>\n" + " <dt>Ki6</dt><dd>no match</dd>\n" + " <dt>Kf9</dt><dd>no match</dd>\n" + " <dt>Qp3</dt><dd>no match</dd>\n" + " <dt>Qd9</dt><dd>no match</dd>\n" + " <dt>Q3</dt><dd>no match</dd>\n" + " <dt>N</dt><dd>no match</dd>\n" + " <dt>Nz9</dt><dd>no match</dd>\n" + " <dt>Na10</dt><dd>no match</dd>\n" + " <dt>B2</dt><dd>no match (watch case)</dd>\n" + " <dt>Bb</dt><dd>no match</dd>\n" + " <dt>Bi4</dt><dd>no match</dd>\n" + " <dt>Ri5</dt><dd>no match</dd>\n" + " <dt>Ra9</dt><dd>no match</dd>\n" + " <dt>Sa2</dt><dd>no match</dd>\n" + " <dt>Zf3</dt><dd>no match</dd>\n" + " <dt>Jj2</dt><dd>no match</dd>\n" + " <dt>1-1</dt><dd>no match</dd>\n" + " <dt>0</dt><dd>no match</dd>\n" + " <dt>2-1</dt><dd>no match</dd>\n" + " <dt>0-1</dt><dd>no match</dd>\n" + " <dt>0-0-1</dt><dd>no match</dd>\n" + " <dt>0-0-0-0</dt><dd>no match</dd>\n" + " <dt>0--0</dt><dd>no match</dd>\n" + " <dt>bxa9</dt><dd>no match</dd>\n" + " <dt>hxi2</dt><dd>no match</dd>\n" + " <dt>Kxf9</dt><dd>no match</dd>\n" + " <dt>Qxp3</dt><dd>no match</dd>\n" + " <dt>Nxz9</dt><dd>no match</dd>\n" + " <dt>Bxi4</dt><dd>no match</dd>\n" + " <dt>Rxi5</dt><dd>no match</dd>\n" + " <dt>a1=</dt><dd>no match</dd>\n" + " <dt>a2=Q</dt><dd>no match</dd>\n" + " <dt>b4=N</dt><dd>no match</dd>\n" + " <dt>d1=S</dt><dd>no match</dd>\n" + " <dt>d5=G</dt><dd>no match</dd>\n" + " <dt>exd5=G</dt><dd>no match</dd>\n" + " <dt>exd1=S</dt><dd>no match</dd>\n" + " <dt>bxa1=</dt><dd>no match</dd>\n" + " <dt>Rdxd2</dt><dd>no match</dd>\n" + " <dt>Rexe2</dt><dd>no match</dd>\n" + " <dt>R2xe2</dt><dd>no match</dd>\n" + " <dt>Bxi4++</dt><dd>no match</dd>"; 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