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"
"
mg

Test String

Substitution

Processing...

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 = "^(\\.?\\w+)(?: (\\w+))(( \\S+)*)"; final String string = "# Circuit generated by QLib\n" + "# Cuccaro's Adder\n" + "# arXiv:quant-ph/0410184v1 \n" + "# 15 bit quantum adder\n\n" + ".qubit 32\n\n" + "qubit c0\n" + "qubit a0\n" + "qubit b0\n" + "qubit a1\n" + "qubit b1\n" + "qubit a2\n" + "qubit b2\n" + "qubit a3\n" + "qubit b3\n" + "qubit a4\n" + "qubit b4\n" + "qubit a5\n" + "qubit b5\n" + "qubit a6\n" + "qubit b6\n" + "qubit a7\n" + "qubit b7\n" + "qubit a8\n" + "qubit b8\n" + "qubit a9\n" + "qubit b9\n" + "qubit a10\n" + "qubit b10\n" + "qubit a11\n" + "qubit b11\n" + "qubit a12\n" + "qubit b12\n" + "qubit a13\n" + "qubit b13\n" + "qubit a14\n" + "qubit b14\n" + "qubit z\n\n" + ".begin\n" + "CNOT a0 b0\n" + "CNOT a0 c0\n" + "Toffoli c0 b0 a0\n" + "CNOT a1 b1\n" + "CNOT a1 a0\n" + "Toffoli a0 b1 a1\n" + "CNOT a2 b2\n" + "CNOT a2 a1\n" + "Toffoli a1 b2 a2\n" + "CNOT a3 b3\n" + "CNOT a3 a2\n" + "Toffoli a2 b3 a3\n" + "CNOT a4 b4\n" + "CNOT a4 a3\n" + "Toffoli a3 b4 a4\n" + "CNOT a5 b5\n" + "CNOT a5 a4\n" + "Toffoli a4 b5 a5\n" + "CNOT a6 b6\n" + "CNOT a6 a5\n" + "Toffoli a5 b6 a6\n" + "CNOT a7 b7\n" + "CNOT a7 a6\n" + "Toffoli a6 b7 a7\n" + "CNOT a8 b8\n" + "CNOT a8 a7\n" + "Toffoli a7 b8 a8\n" + "CNOT a9 b9\n" + "CNOT a9 a8\n" + "Toffoli a8 b9 a9\n" + "CNOT a10 b10\n" + "CNOT a10 a9\n" + "Toffoli a9 b10 a10\n" + "CNOT a11 b11\n" + "CNOT a11 a10\n" + "Toffoli a10 b11 a11\n" + "CNOT a12 b12\n" + "CNOT a12 a11\n" + "Toffoli a11 b12 a12\n" + "CNOT a13 b13\n" + "CNOT a13 a12\n" + "Toffoli a12 b13 a13\n" + "CNOT a14 b14\n" + "CNOT a14 a13\n" + "Toffoli a13 b14 a14\n" + "CNOT a14 z\n" + "Toffoli a13 b14 a14\n" + "CNOT a14 a13\n" + "CNOT a13 b14\n" + "Toffoli a12 b13 a13\n" + "CNOT a13 a12\n" + "CNOT a12 b13\n" + "Toffoli a11 b12 a12\n" + "CNOT a12 a11\n" + "CNOT a11 b12\n" + "Toffoli a10 b11 a11\n" + "CNOT a11 a10\n" + "CNOT a10 b11\n" + "Toffoli a9 b10 a10\n" + "CNOT a10 a9\n" + "CNOT a9 b10\n" + "Toffoli a8 b9 a9\n" + "CNOT a9 a8\n" + "CNOT a8 b9\n" + "Toffoli a7 b8 a8\n" + "CNOT a8 a7\n" + "CNOT a7 b8\n" + "Toffoli a6 b7 a7\n" + "CNOT a7 a6\n" + "CNOT a6 b7\n" + "Toffoli a5 b6 a6\n" + "CNOT a6 a5\n" + "CNOT a5 b6\n" + "Toffoli a4 b5 a5\n" + "CNOT a5 a4\n" + "CNOT a4 b5\n" + "Toffoli a3 b4 a4\n" + "CNOT a4 a3\n" + "CNOT a3 b4\n" + "Toffoli a2 b3 a3\n" + "CNOT a3 a2\n" + "CNOT a2 b3\n" + "Toffoli a1 b2 a2\n" + "CNOT a2 a1\n" + "CNOT a1 b2\n" + "Toffoli a0 b1 a1\n" + "CNOT a1 a0\n" + "CNOT a0 b1\n" + "Toffoli c0 b0 a0\n" + "CNOT a0 c0\n" + "CNOT c0 b0\n" + ".end\n\n" + "# Circuit generated by QLib\n" + "# Bernstein-Vazirani search\n" + "# Secret= 1\n" + ".qubit 11\n" + "qubit x0 \n" + "qubit x1 \n" + "qubit x2 \n" + "qubit x3 \n" + "qubit x4 \n" + "qubit x5 \n" + "qubit x6 \n" + "qubit x7 \n" + "qubit x8 \n" + "qubit x9 \n" + "qubit y\n" + "Prep0 y\n" + ".begin\n" + "X y\n" + "H x0\n" + "H x1\n" + "H x2\n" + "H x3\n" + "H x4\n" + "H x5\n" + "H x6\n" + "H x7\n" + "H x8\n" + "H x9\n" + "H y\n" + "CNOT x0 y\n" + "H x0\n" + "H x1\n" + "H x2\n" + "H x3\n" + "H x4\n" + "H x5\n" + "H x6\n" + "H x7\n" + "H x8\n" + "H x9\n" + "H y\n" + ".end\n\n" + "# Circuit generated by QLib\n" + "# QFT for 15 qubits\n" + ".qubit 15\n\n" + "qubit q0\n" + "qubit q1\n" + "qubit q2\n" + "qubit q3\n" + "qubit q4\n" + "qubit q5\n" + "qubit q6\n" + "qubit q7\n" + "qubit q8\n" + "qubit q9\n" + "qubit q10\n" + "qubit q11\n" + "qubit q12\n" + "qubit q13\n" + "qubit q14\n\n" + ".begin\n" + "H q0\n" + "CP q1 q0 2\n" + "CP q2 q0 1\n" + "CP q3 q0 0.5\n" + "CP q4 q0 0.25\n" + "CP q5 q0 0.125\n" + "CP q6 q0 0.0625\n" + "CP q7 q0 0.03125\n" + "CP q8 q0 0.015625\n" + "CP q9 q0 0.0078125\n" + "CP q10 q0 0.00390625\n" + "CP q11 q0 0.00195312\n" + "CP q12 q0 0.000976562\n" + "CP q13 q0 0.000488281\n" + "CP q14 q0 0.000244141\n" + "H q1\n" + "CP q2 q1\n" + "CP q3 q1 1\n" + "CP q4 q1 0.5\n" + "CP q5 q1 0.25\n" + "CP q6 q1 0.125\n" + "CP q7 q1 0.0625\n" + "CP q8 q1 0.03125\n" + "CP q9 q1 0.015625\n" + "CP q10 q1 0.0078125\n" + "CP q11 q1 0.00390625\n" + "CP q12 q1 0.00195312\n" + "CP q13 q1 0.000976562\n" + "CP q14 q1 0.000488281\n" + "H q2\n" + "CP q3 q2 2\n" + "CP q4 q2 1\n" + "CP q5 q2 0.5\n" + "CP q6 q2 0.25\n" + "CP q7 q2 0.125\n" + "CP q8 q2 0.0625\n" + "CP q9 q2 0.03125\n" + "CP q10 q2 0.015625\n" + "CP q11 q2 0.0078125\n" + "CP q12 q2 0.00390625\n" + "CP q13 q2 0.00195312\n" + "CP q14 q2 0.000976562\n" + "H q3\n" + "CP q4 q3 2\n" + "CP q5 q3 1\n" + "CP q6 q3 0.5\n" + "CP q7 q3 0.25\n" + "CP q8 q3 0.125\n" + "CP q9 q3 0.0625\n" + "CP q10 q3 0.03125\n" + "CP q11 q3 0.015625\n" + "CP q12 q3 0.0078125\n" + "CP q13 q3 0.00390625\n" + "CP q14 q3 0.00195312\n" + "H q4\n" + "CP q5 q4 2\n" + "CP q6 q4 1\n" + "CP q7 q4 0.5\n" + "CP q8 q4 0.25\n" + "CP q9 q4 0.125\n" + "CP q10 q4 0.0625\n" + "CP q11 q4 0.03125\n" + "CP q12 q4 0.015625\n" + "CP q13 q4 0.0078125\n" + "CP q14 q4 0.00390625\n" + "H q5\n" + "CP q6 q5 2\n" + "CP q7 q5 1\n" + "CP q8 q5 0.5\n" + "CP q9 q5 0.25\n" + "CP q10 q5 0.125\n" + "CP q11 q5 0.0625\n" + "CP q12 q5 0.03125\n" + "CP q13 q5 0.015625\n" + "CP q14 q5 0.0078125\n" + "H q6\n" + "CP q7 q6 2\n" + "CP q8 q6 1\n" + "CP q9 q6 0.5\n" + "CP q10 q6 0.25\n" + "CP q11 q6 0.125\n" + "CP q12 q6 0.0625\n" + "CP q13 q6 0.03125\n" + "CP q14 q6 0.015625\n" + "H q7\n" + "CP q8 q7 2\n" + "CP q9 q7 1\n" + "CP q10 q7 0.5\n" + "CP q11 q7 0.25\n" + "CP q12 q7 0.125\n" + "CP q13 q7 0.0625\n" + "CP q14 q7 0.03125\n" + "H q8\n" + "CP q9 q8 2\n" + "CP q10 q8 1\n" + "CP q11 q8 0.5\n" + "CP q12 q8 0.25\n" + "CP q13 q8 0.125\n" + "CP q14 q8 0.0625\n" + "H q9\n" + "CP q10 q9 2\n" + "CP q11 q9 1\n" + "CP q12 q9 0.5\n" + "CP q13 q9 0.25\n" + "CP q14 q9 0.125\n" + "H q10\n" + "CP q11 q10 2\n" + "CP q12 q10 1\n" + "CP q13 q10 0.5\n" + "CP q14 q10 0.25\n" + "H q11\n" + "CP q12 q11 2\n" + "CP q13 q11 1\n" + "CP q14 q11 0.5\n" + "H q12\n" + "CP q13 q12 2\n" + "CP q14 q12 1\n" + "H q13\n" + "CP q14 q13 2\n" + "H q14\n" + ".end\n\n\n"; final String subst = ""; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); // The substituted value will be contained in the result variable final String result = matcher.replaceAll(subst); System.out.println("Substitution result: " + result); } }

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