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

/
/
g

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"\/\\*[^*]*\\*+(?:[^\/*][^*]*\\*+)*\/|\/\/.*" test_str = ("import android.content.res.Resources;\n" " import android.os.Handler;\n" " import android.preference.PreferenceFragment;\n" " import android.view.ViewGroup;\n" " * Provides the regex to identify domain HTTP(S) protocol and/or 'www' sub-domain.\n" " *\n" " * Used to format user-facing {@link String}'s in certain preferences.\n" " */\n" " public static final String ADDRESS_FORMAT_REGEX = \"^(https?://(w{3})?|www\\\\.)\";\n\n" " /**\n" " // Used to ensure that settings are only fetched once throughout the lifecycle of the fragment\n" " private boolean mShouldFetch;\n\n" " public View onCreateView(@NonNull LayoutInflater inflater,\n" " ViewGroup container,\n" " Bundle savedInstanceState) {\n" " // use a wrapper to apply the Calypso theme\n" " Context themer = new ContextThemeWrapper(getActivity(), R.style.Calypso_SiteSettingsTheme);\n" " LayoutInflater localInflater = inflater.cloneInContext(themer);\n" " View view = super.onCreateView(localInflater, container, savedInstanceState);\n\n" " if (view != null) {\n" " setupPreferenceList((ListView) view.findViewById(android.R.id.list), getResources());\n" " }\n\n" " return view;\n" " }\n\n" " @Override\n" " public void onChildViewAdded(View parent, View child) {\n" " if (child.getId() == android.R.id.title && child instanceof TextView) {\n" " // style preference category title views\n" " TextView title = (TextView) child;\n" " WPPrefUtils.layoutAsBody2(title);\n" " } else {\n" " // style preference title views\n" " TextView title = (TextView) child.findViewById(android.R.id.title);\n" " if (title != null) WPPrefUtils.layoutAsSubhead(title);\n" " }\n" " }\n\n" " @Override\n" " public void onChildViewRemoved(View parent, View child) {\n" " // NOP\n" " }\n\n" " @Override") matches = re.finditer(regex, test_str) 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