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

/
/
gm

Test String

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"\b(?:https?:\/\/)(?:www\d?\.)?[-\w\d&#%?\/=\.+]+\b" 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 = re.finditer(regex, test_str, re.MULTILINE) for matchNum, match in enumerate(matches, start=1): print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group())) for groupNum in range(0, len(match.groups())): groupNum = groupNum + 1 print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum))) # 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