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"^(PO BOX|BOX)+\s*[A-Z]?[0-9]+[A-Z]*\s.*$" test_str = ("BOX ELDER CT\n" "PO BOX 111 \n" "PO BOX 191 \n" "39TH ST\n" "6TH ST\n" "4TH AVE\n" "5TH AVE\n" "5TH ST\n" "2ND AVE\n" "15TH AVE\n" "BOX ELDER DR\n" "PO BOX 297 \n" "PO BOX 42 \n" "PO BOX 18 \n" "PO BOX 16 \n" "PO BOX 115A \n" "PO BOX 245 \n" "PO BOX 131 \n" "PO BOX 254 \n" "PO BOX 254 \n" "PO BOX 49B \n" "PO BOX 373 \n" "PO BOX 178 \n" "PO BOX 245 \n" "PO BOX 51 \n" "PO BOX 400 \n" "PO BOX 25 \n" "PO BOX 25 \n" "PO BOX 7 \n" "PO BOX 97 \n" "PO BOX 363 \n" "PO BOX 482 \n" "PO BOX 24 \n" "PO BOX 55 \n" "PO BOX 204 \n" "PO BOX 482 \n" "PO BOX 331 \n" "PO BOX 99 \n" "PO BOX 204 \n" "PO BOX 224C \n" "BOX 246 \n" "BOX 2005 \n" "BOX 431 ATLAN & CLEV \n" "BOX 384 \n" "BOX 22 \n" "BOX 247 \n" "BOX 212 \n" "BOX 85 \n" "PO BOX 192 \n" "PO BOX 192 \n" "BOX 232 \n" "BOX 28 \n" "PO BOX A73 \n" "PO BOX 53 \n" "BOX 4 \n" "PO BOX 266 \n" "BOX 154 \n" "BOX 261 \n" "BOX 82 \n" "BOX ELDER LN\n" "BOX 101 \n" "PO BOX 76 EAST MARKET ") 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