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

/
/
gm

Test String

Code Generator

Generated Code

const regex = /(?:^|[^%])(?:%%)*(%(?:\d+\$)?(?:\+)?(?:0|'.)?(?:\-)?(?:\d+)?(?:\.\d+)?[bcdeEufFgGosxX])/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?:^|[^%])(?:%%)*(%(?:\\d+\\$)?(?:\\+)?(?:0|\'.)?(?:\\-)?(?:\\d+)?(?:\\.\\d+)?[bcdeEufFgGosxX])', 'gm') const str = `<?php \$n = 43951789; \$u = -43951789; \$c = 65; // ASCII コードの 65 は 'A' です // %% 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 printf("%%b = '%b'\\n", \$n); // 2 進表現 printf("%%c = '%c'\\n", \$c); // ascii 文字を表示します。chr() 関数と同じです printf("%%d = '%d'\\n", \$n); // 標準の整数表現 printf("%%e = '%e'\\n", \$n); // 科学記法 printf("%%u = '%u'\\n", \$n); // 正の整数の、符号なし整数表現 printf("%%u = '%u'\\n", \$u); // 負の整数の、符号なし整数表現 printf("%%f = '%f'\\n", \$n); // 浮動小数点表現 printf("%%o = '%o'\\n", \$n); // 8 進表現 printf("%%s = '%s'\\n", \$n); // 文字列表現 printf("%%x = '%x'\\n", \$n); // 16 進表現 (小文字) printf("%%X = '%X'\\n", \$n); // 16 進表現 (大文字) printf("%%+d = '%+d'\\n", \$n); // 正の整数に符号指定子を使用 printf("%%+d = '%+d'\\n", \$u); // 負の整数に符号指定子を使用 ?> <?php \$s = 'monkey'; \$t = 'many monkeys'; printf("[%s]\\n", \$s); // 標準の文字列出力 printf("[%10s]\\n", \$s); // 空白を使用して右詰め printf("[%-10s]\\n", \$s); // 空白を使用して左詰め printf("[%010s]\\n", \$s); // ゼロ埋めは文字列でも可能です printf("[%'#10s]\\n", \$s); // ゼロの代わりに独自の文字 '#' で埋めます printf("[%10.10s]\\n", \$t); // 左詰めを行い、10 文字以上は切り捨てます ?> 例9 sprintf(): 整数のゼロ埋め <?php \$isodate = sprintf("%04d-%02d-%02d", \$year, \$month, \$day); ?> 例10 sprintf(): 通貨をフォーマットする例 <?php \$money1 = 68.75; \$money2 = 54.35; \$money = \$money1 + \$money2; // echo \$money は "123.1" を出力します。 \$formatted = sprintf("%01.2f", \$money); // echo \$formatted は "123.10"を出力します ?> 例11 sprintf(): 科学記法 <?php \$number = 362525200; echo sprintf("%.3e", \$number); // 3.625e+8 を出力します ?> `; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; while ((m = regex.exec(str)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === regex.lastIndex) { regex.lastIndex++; } // The result can be accessed through the `m`-variable. m.forEach((match, groupIndex) => { console.log(`Found match, group ${groupIndex}: ${match}`); }); }

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 JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions