Regular Expressions 101

Save & Manage Regex

  • Current Version: 1
  • Save & Share
  • Community Library

Flavor

  • PCRE2 (PHP)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java
  • .NET 7.0 (C#)
  • Rust
  • PCRE (Legacy)
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests
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
Processing...

Test String

Code Generator

Language

Generated Code

import re regex = re.compile(r"\b(?:https?:\/\/)(?:www\d?\.)?[-\w\d&#%?\/=\.+]+\b", flags=re.MULTILINE) test_str = ("HEN 1 ELSE 0 END AS CONNECT_BY_ISBRANCH\n" " , CASE WHEN t.id IN (SELECT parent_id FROM tbl) THEN 0 ELSE 1 END AS CONNECT_BY_ISLEAF\n" " , CASE WHEN th.SYS_CONNECT_BY_PATH_id LIKE '%/' + CAST(t.id AS VARCHAR(MAX)) + '/%'\n" " THEN 1 ELSE 0 END AS CONNECT_BY_ISCYCLE\n" " , th.SYS_CONNECT_BY_PATH_id + CAST(t.id AS VARCHAR(MAX)) + '/' AS SYS_CONNECT_BY_PATH_id\n" " , th.SYS_CONNECT_BY_PATH_name + CAST(t.name AS VARCHAR(MAX)) + '/' AS SYS_CONNECT_BY_PATH_name\n" " , th.root_id\n" " , t.*\n" " FROM tbl t\n" " JOIN tbl_hierarchy th ON (th.id = t.parent_id) -- CONNECT BY PRIOR id = parent_id\n" " WHERE th.CONNECT_BY_ISCYCLE = 0) -- NOCYCLE\n" "SELECT th.*\n" " --, REPLICATE(' ', (th.\"LEVEL\" - 1) * 3) + th.name AS tbl_hierarchy\n" " FROM tbl_hierarchy th\n" " JOIN tbl CONNECT_BY_ROOT ON (CONNECT_BY_ROOT.id = th.root_id)\n" " ORDER BY th.SYS_CONNECT_BY_PATH_name; -- ORDER SIBLINGS BY name\n" "هذا شرح لميزات CONNECT BY الموضّحة أعلاه:\n\n\n" "https://academy.hsoub.com/programming/sql/%D8%A7%D9%84%D8%AA%D8%B9%D8%A7%D8%A8%D9%8A%D8%B1-%D8%A7%D9%84%D8%AC%D8%AF%D9%88%D9%84%D9%8A%D8%A9-%D8%A7%D9%84%D8%B4%D8%A7%D8%A6%D8%B9%D8%A9-common-table-expressions-%D9%81%D9%8A-sql-r856/\n\n" "and http://www.watheq.xyz/ and https://twitter.com/home\n" " \n" "العبارات\n" "CONNECT BY: تحدّد العلاقة التي تعرّف التشعّب\n" "START WITH: تحدّد العقدة الجذرية (root nodes).\n" "ORDER SIBLINGS BY: تحدّد ترتيب النتائج\n" "المعاملات\n" "NOCYCLE: توقِف معالجة فرع معيّن عند رصد شعبة دورية (loop). لأنّ الشعب الصالحة هي الشعب غير الدورية (Directed Acyclic)، أي الشعب التي لا يمكن العودة عبرها إلى العقدة نفسها.\n" "العمليات\n" "PRIOR: تحصل على البيانات من العقدة الأب (node's parent).\n" "CONNECT_BY_ROOT: تحصل على البيانات من العقدة الجذرية.\n" "أشباه الأعمدة Pseudocolumns\n" "LEVEL: تشير إلى مسافة العقدة من جذرها.\n" "CONNECT_BY_ISLEAF: تشير إلى عقدة بدون فروعها.\n" "CONNECT_BY_ISCYCLE: تشير إلى عقدة ذات مرجع دائري (circular reference).\n" "الدوال\n" "SYS_CONNECT_BY_PATH: تعيد سلسلة نصية تمثّل المسار من الجذر إلى العقدة.\n" "ترجمة -وبتصرّف- للفصل 46 من الكتاب SQL Notes for Professionals") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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