Regular Expressions 101

Save & Share

  • Regex Version: ver. 1
  • Update Regex
    ctrl+⇧+s
  • Save new Regex
    ctrl+s
  • Add to Community Library

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r"^(\.?\w+)(?: (\w+))(( \S+)*)" test_str = ("# 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") subst = "" # You can manually specify the number of replacements by changing the 4th argument result = re.sub(regex, subst, test_str, 0, re.MULTILINE) if result: print (result) # Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

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 Python, please visit: https://docs.python.org/3/library/re.html