10 Questions
What is the purpose of the \b anchor in regular expressions?
To match a word boundary
What is the difference between a capturing group and a non-capturing group in regular expressions?
A capturing group remembers the match, while a non-capturing group does not
What is the purpose of the (?:abc) syntax in regular expressions?
To create a non-capturing group
What does the quantifier a{1,3} match in regular expressions?
Between one and three 'a' characters
What is the purpose of the \W character class in regular expressions?
To match a non-word character
What does the character class [a-g] match in regular expressions?
any character between a and g
What is the purpose of the character in regular expressions?
to match a tab character
What does the regular expression a{2,} match?
two or more a's
What is the purpose of the (?=abc) syntax in regular expressions?
to match abc without including it in the match
What does the regular expression a+?a{2,}? match?
as few a's as possible, followed by two or more a's
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
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
Test your understanding of character classes, anchors, and groups in regular expressions. Learn to match patterns and create efficient regex expressions.
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