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Questions and Answers
What is the purpose of the \b anchor in regular expressions?
What does the [a-g] pattern match in regular expressions?
What is the purpose of a non-capturing group in regular expressions?
What does the \W pattern match in regular expressions?
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What is the purpose of the a{1,3} quantifier in regular expressions?
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Study Notes
Character Classes
- Any character except newline:
\w,\d,\smatch word, digit, whitespace respectively - Not word, digit, whitespace:
\W,\D,\Srespectively - Match any of a, b, or c:
[abc] - Not a, b, or c:
[^abc] - Character between a & g:
[a-g]
Anchors
- Start of the string:
^ - End of the string:
$ - Word boundary:
\b - Not-word boundary:
\B
Escaped Characters
- Escaped special characters:
\.,\\ - Tab, linefeed, carriage return:
\t,\n,\r
Groups & Lookaround
- Capture group:
(abc) - Backreference to group #1:
\1 - Non-capturing group:
(?:abc) - Positive lookahead:
(?=abc) - Negative lookahead:
(?!abc)
Quantifiers & Alternation
- 0 or more, 1 or more, 0 or 1:
a*,a+,a? - Exactly five, two or more:
a{5},a{2,} - Between one & three:
a{1,3} - Match as few as possible:
a+?,a{2,}? - Match ab or cd:
ab|cd
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Description
Understanding character classes, anchors, escaped characters, groups, and lookaround in regular expressions. Learn about pattern matching techniques in programming.
