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

import Foundation let pattern = #"(.*)@(?!gmail)\w+\.com"# let regex = try! NSRegularExpression(pattern: pattern) let testString = ##""" # 配對電子郵件 # 題目說明區塊 請幫我抓出@(小老鼠)前面的帳戶名稱，而且我不要 gmail 的。 #欲測試資料集 foobar@gmail.com NoOneCareMe@gamil.com SaveTheWorld@hotmail.com zzzGroup@yahoo.com eagle1963@gmail.com maythefourthwithyiu@starwars.com # 應配對結果(亮色區塊) NoOneCareMe@gamil.com SaveTheWorld@hotmail.com zzzGroup@yahoo.com maythefourthwithyiu@starwars.com # (選項)寫上註解，好好說明你怎麼想的 首先將 @ 之前的文字都抓起來，所以放上()，因為不想顧及裡面的文字是什麼，所以很懶惰的使用 .*，步驟多了點但是我不在意ＸＤ，因為不想要 gmail 所以我再任意文字 \w+ 前面判斷寫上不是 gmail，最後放上 \.com來玩成此次配對，希望你可以幫我減少更多 step(步驟)，來提高這個規則的效率。 # (選項)將你的 Regex 註解起來，使用 Extended Formating / # Start of Regex ( # Group and Capturing follwoing .* # Match any form zero-to-many ) # End of group @ # Match @ ( # Group and Capturing follwoing ?! # Negative lookahead gmail # Match Gmail ) # End of group \w+ # Match any character from one-to-many \. # Match .(dot) com # Match com / # End of Regex """## let stringRange = NSRange(location: 0, length: testString.utf16.count) let matches = regex.matches(in: testString, range: stringRange) var result: [[String]] = [] for match in matches { var groups: [String] = [] for rangeIndex in 1 ..< match.numberOfRanges { let nsRange = match.range(at: rangeIndex) guard !NSEqualRanges(nsRange, NSMakeRange(NSNotFound, 0)) else { continue } let string = (testString as NSString).substring(with: nsRange) groups.append(string) } if !groups.isEmpty { result.append(groups) } } print(result)

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 Swift 5.2, please visit: https://developer.apple.com/documentation/foundation/nsregularexpression