Regex

Question 1

g

Answer 1

Global match — find all matches rather than only the first one

Question 2

m

Answer 2

Multi-line match — tells the engine to treat the subject string as multiple lines. ^ and $ match next to \n instead of the start or end of the entire string

Question 3

i

Answer 3

Ignore case — match both lower and upper case letters

Question 4

.

Answer 4

Matches any single character except the newline character. Example: .at matches bat, cat, rat and also .at, 1atEquivalent to [^\x0A\x0D\u2028\u2029]

Question 5

[^…]

Answer 5

The negated bracket expression or negated character class matches any single character not contained within the brackets or range of characters. Same as above, except that the ^ negates the expression. Example: [0-9] matches any character that's not a number.Although the ^ character is a special character, it doesn't need to be escaped within the brackets in order to be treated as a literal. Example: [^] matches anything, [^^] matches anything except the ^ character.

Question 6

\w

Answer 6

Word character| Equivalent to [A-Za-z0-9_]

Question 7

\W

Answer 7

Non-word character| Equivalent to [^A-Za-z0-9_]

Question 8

\d

Answer 8

Digit character| Equivalent to [0-9]

Question 9

\D

Answer 9

Non-digit character| Equivalent to [^0-9]

Question 10

\s

Answer 10

Whitespace characterEquivalent to [\f\n\r\t\v\u00A0\u2028\u2029] (\u00A0 means “no-break space”, \u2028 means “line separator”, \u2029 means “paragraph separator”)

Question 11

\S

Answer 11

Non-whitespace character| Equivalent to [^\f\n\r\t\v\u00A0\u2028\u2029]

Question 12

\b

Answer 12

Word Boundary| Backspace (\x08)

Question 13

\f

Answer 13

Form-feed (\x0C)

Question 14

\n

Answer 14

Linefeed or newline (\x0A)

Question 15

\r

Answer 15

Carriage return (\x0D)

Question 16

\t

Answer 16

Tab (\x09)

Question 17

\v

Answer 17

Vertical tab (\x0B)

Question 18

\0

Answer 18

Null character (\x00)

Question 19

\xhh

Answer 19

Character with hexadecimal code hh.

Question 20

\uhhhh

Answer 20

Character with hexadecimal code hhhh.

Question 21

[…]

Answer 21

The bracket expression specifies a character class and matches any single character contained within the brackets or range of characters. Example: [abc] matches a, b and/or c, in any order.A range of characters is specified using the -, for example [a-z] matches any lowercase ASCII letter from a to z. Other examples include [A-F] which matches any uppercase ASCII letter from A to F, and [4-7] which matches any number from 4 to 7. The - character is treated as a literal character if it's listed first, last or escaped: [-] matches -, [a-] matches a and/or -, [a\-z] matches a, - and/or z.Additionally, listed characters can be mixed with ranges of characters. Example: [0-9a-fA-F] matches any number and also letters from a to z irrespective of their case, [02468aeiouy-] matches even numbers, vowels and the - character.Brackets inside bracket expressions are treated as literals if they are escaped. Example: [\[\]] matches [ and/or ]. The [ doesn't need to be escaped if it's listed first: [[] matches [

Question 22

?

Answer 22

Match 0 or 1 times. Example: ab? matches a and ab

Question 23

+

Answer 23

Match 1 or more times. Example: ab+ matches ab, abb, abbb etc.

Question 24

{n}

Answer 24

Match exactly n times. Example: ab{2} matches abb

Question 25

{n,}

Answer 25

Match n or more times. Example: ab{2,} matches abb, abbb, abbbb etc.

Question 26

{n,m}

Answer 26

Match at least n times, but no more than m times. Example: ab{2,3} matches abb and abbb

Question 27

??

Answer 27

Match 0 or 1 times, but as few times as possible. Example: ab?? against abbbbb matches a

Question 28

*?

Answer 28

Match 0 or more times, but as few times as possible. Example: ab*? against abbbbb matches a

Question 29

+?

Answer 29

Match 1 or more times, but as few times as possible. Example: ab+? against abbbbb matches ab

Question 30

{n}?

Answer 30

Match n or more times, but as few times as possible. Example: ab{2}? against abbbbb matches abb

Question 31

{n,m}?

Answer 31

Match at least n times, no more than m times, but as few times as possible. Example: ab{2,3}? against abbbbb matches abb

Question 32

*

Answer 32

Match 0 or more times. Example: ab* matches a, ab, abb, abbb etc.

Question 33

(…)

Answer 33

Capturing group - group subpattern and capture the match. Example: (foo)bar matches foobar and captures foo

Question 34

…|…

Answer 34

Alternation operator - matches one of the alternative subppatterns. Example: foo|bar|baz matches either foo, bar or baz

Question 35

(?:…)

Answer 35

Non-capturing group - group subpattern, but don’t capture the match. Example: (?:foo)bar matches foobar and doesn’t capture anything

Question 36

Matches any single character except the newline character.

Answer 36

.

Question 37

The bracket expression.

Answer 37

[…]

Question 38

The negated bracket expression.

Answer 38

[^…]

Question 39

Word character Equivalent to [A-Za-z0-9_]

Answer 39

\w

Question 40

Non-word characterEquivalent to [^A-Za-Non-word characterEquivalent to [^A-Za-z0-9_]

Answer 40

\W

Question 41

Digit characterEquivalent to [0-9]

Answer 41

\d

Question 42

Non-digit characterEquivalent to [^0-9]

Answer 42

\D

Question 43

Whitespace characterEquivalent to [\f\n\r\t\v\u00A0\u2028\u2029] (\u00A0 means “no-break space”, \u2028 means “line separator”, \u2029 means “paragraph separator”)

Answer 43

\s

Question 44

Non-whitespace characterEquivalent to [^\f\n\r\t\v\u00A0\u2028\u2029]

Answer 44

\S

Question 45

Word Boundary| Backspace (\x08)

Answer 45

\b

Question 46

Form-feed (\x0C)

Answer 46

\f

Question 47

Linefeed or newline (\x0A)

Answer 47

\n

Question 48

Carriage return (\x0D)

Answer 48

\r

Question 49

Tab (\x09)

Answer 49

\t

Question 50

Vertical tab (\x0B)

Answer 50

\v

Question 51

Null character (\x00)

Answer 51

\0

Question 52

Character with hexadecimal code hh.

Answer 52

\xhh

Question 53

Character with hexadecimal code hhhh.

Answer 53

\uhhhh