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"(?:^|[^%])(?:%%)*(%(?:\d+\$)?(?:\+)?(?:0|'.)?(?:\-)?(?:\d+)?(?:\.\d+)?[bcdeEufFgGosxX])" test_str = ("<?php\n" "$n = 43951789;\n" "$u = -43951789;\n" "$c = 65; // ASCII コードの 65 は 'A' です\n\n" "// %% に注目しましょう。これは、リテラル '%' を文字として出力します\n" "printf(\"%%b = '%b'\\n\", $n); // 2 進表現\n" "printf(\"%%c = '%c'\\n\", $c); // ascii 文字を表示します。chr() 関数と同じです\n" "printf(\"%%d = '%d'\\n\", $n); // 標準の整数表現\n" "printf(\"%%e = '%e'\\n\", $n); // 科学記法\n" "printf(\"%%u = '%u'\\n\", $n); // 正の整数の、符号なし整数表現\n" "printf(\"%%u = '%u'\\n\", $u); // 負の整数の、符号なし整数表現\n" "printf(\"%%f = '%f'\\n\", $n); // 浮動小数点表現\n" "printf(\"%%o = '%o'\\n\", $n); // 8 進表現\n" "printf(\"%%s = '%s'\\n\", $n); // 文字列表現\n" "printf(\"%%x = '%x'\\n\", $n); // 16 進表現 (小文字)\n" "printf(\"%%X = '%X'\\n\", $n); // 16 進表現 (大文字)\n\n" "printf(\"%%+d = '%+d'\\n\", $n); // 正の整数に符号指定子を使用\n" "printf(\"%%+d = '%+d'\\n\", $u); // 負の整数に符号指定子を使用\n" "?>\n\n" "<?php\n" "$s = 'monkey';\n" "$t = 'many monkeys';\n\n" "printf(\"[%s]\\n\", $s); // 標準の文字列出力\n" "printf(\"[%10s]\\n\", $s); // 空白を使用して右詰め\n" "printf(\"[%-10s]\\n\", $s); // 空白を使用して左詰め\n" "printf(\"[%010s]\\n\", $s); // ゼロ埋めは文字列でも可能です\n" "printf(\"[%'#10s]\\n\", $s); // ゼロの代わりに独自の文字 '#' で埋めます\n" "printf(\"[%10.10s]\\n\", $t); // 左詰めを行い、10 文字以上は切り捨てます\n" "?>\n" "例9 sprintf(): 整数のゼロ埋め\n\n" "<?php\n" "$isodate = sprintf(\"%04d-%02d-%02d\", $year, $month, $day);\n" "?>\n" "例10 sprintf(): 通貨をフォーマットする例\n\n" "<?php\n" "$money1 = 68.75;\n" "$money2 = 54.35;\n" "$money = $money1 + $money2;\n" "// echo $money は \"123.1\" を出力します。\n" "$formatted = sprintf(\"%01.2f\", $money);\n" "// echo $formatted は \"123.10\"を出力します\n" "?>\n" "例11 sprintf(): 科学記法\n\n" "<?php\n" "$number = 362525200;\n\n" "echo sprintf(\"%.3e\", $number); // 3.625e+8 を出力します\n" "?>\n\n") 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