RegEx Special Characters

Question 1

\d

Answer 1

-Matches a digit from 0 to 9

“1”
“A” (no match)
“_” (no match)
“!” (no match)
“ ” (no match)

Question 2

\d

Answer 2

-Matches a digit from 0 to 9

“1”
“A” (no match)
“_” (no match)
“!” (no match)
“ ” (no match)

Question 3

\D

Answer 3

-Matches a non-digit

“1” (no match)
“A”
“_”
“!”
“ ”

Question 4

\w

Answer 4

-Matches a word character (letter, digit, or underscore)

“1”
“A”
“_”
“!” (no match)
“ ” (no match)

Question 5

\W

Answer 5

-Matches any non-word characters

“1” (no match)
“A” (no match)
“_” (no match)
“!”
“ ”

Question 6

\s

Answer 6

-Matches any whitespace character, such as spaces and tabs

“1” (no match)
“A” (no match)
“_” (no match)
“!” (no match)
“ ”

Question 7

\S

Answer 7

-Matches any non-whitespace character

“1”
“A”
“_”
“!”
“ ” (no match)

Question 8

[…]

Answer 8

-Character Set:
+Matches any characters inside the brackets
+Can specify ranges of characters as well

Example set: "[A-C]"
“A”
“B”
“C”
“D” (no match)
“E” (no match)

Question 9

[^…]

Answer 9

-Negative Character Set:
+Matches anything NOT inside the brackets

Example set:"[^C-E]"
“A”
“B”
“C” (no match)
“D” (no match)
“E” (no match)

Question 10

.

Answer 10

-Wildcard: matches any character (except a newline)

“1”
“A”
“_”
“!”
“ ”

Question 11

*

Answer 11

-Matches 0 or more times

Example: "ca*t"
“ct”
“cat”
“caat”
“caaat”
“caaaat”

Question 12

+

Answer 12

-Matches 1 or more times

Example: "ca+t"
“ct” (no match)
“cat”
“caat”
“caaat”
“caaaat”

Question 13

?

Answer 13

-Matches 0 or 1 times

Example: "ca?t"
“ct”
“cat”
“caat” (no match)
“caaat” (no match)
“caaaat” (no match)

Question 14

{#,}

Answer 14

-Matches at least a specific number of times

Example: "ca{2,}t"
“ct” (no match)
“cat” (no match)
“caat”
“caaat”
“caaaat”

Question 15

{# , #}

Answer 15

-Matches within a specific range of times

Example: "ca{2,3}t"
“ct” (no match)
“cat” (no match)
“caat”
“caaat”
“caaaat” (no match)

Question 16

|

Answer 16

-Alteration: matches either the expression before or the expression after (OR)

Example: “cat|dog”
“cat”
“dog”
“bird” (no match)

Answer 17

-Start of the string

Example: "^cat"
“cat”
“catsup”
“concatenate” (no match)
“kitty-cat” (no match)

Question 18

$

Answer 18

-End of the string

Example: "cat$"
“cat”
“catsup” (no match)
“concatenate” (no match)
“kitty-cat”

Answer 19

Escape Character: escapes the next character to be treated as a literal character

Example: /$
“$”

Question 20

( … )

Answer 20

-Capture Group: identifies matches that should be extracted

Example: “c(at)”
“cat” (“at” is captured)
“bat” (no match)

Question 21

(?: … )

Answer 21

-Non-Capturing Group: identifies matches that should not be extracted

Example: “c(?:at)”
“cat” (“c” is captured)
“bat” (no match)

Question 22

(?! … )

Answer 22

-Negative Lookahead Group: identifies expressions that negate earlier matches

Example: “cat(?! burglar)”
“cat”
“cats”
“cat burglar” (no match)

Question 23

\D

Answer 23

-Matches a non-digit

“1” (no match)
“A”
“_”
“!”
“ ”

Question 24

\w

Answer 24

-Matches a word character (letter, digit, or underscore)

“1”
“A”
“_”
“!” (no match)
“ ” (no match)

Question 25

\W

Answer 25

-Matches any non-word characters ``` “1” (no match) “A” (no match) “_” (no match) “!” “ ” ```

Question 26

\s

Answer 26

-Matches any whitespace character, such as spaces and tabs ``` “1” (no match) “A” (no match) “_” (no match) “!” (no match) “ ” ```

Question 27

\S

Answer 27

-Matches any non-whitespace character ``` “1” “A” “_” “!” “ ” (no match) ```

Question 28

[...]

Answer 28

-Character Set: +Matches any characters inside the brackets +Can specify ranges of characters as well ``` Example set: "[A-C]" “A” “B” “C” “D” (no match) “E” (no match) ```

Question 29

[^...]

Answer 29

-Negative Character Set: +Matches anything NOT inside the brackets ``` Example set:"[^C-E]" “A” “B” “C” (no match) “D” (no match) “E” (no match) ```

Question 30

.

Answer 30

-Wildcard: matches any character (except a newline) ``` “1” “A” “_” “!” “ ” ```

Question 31

*

Answer 31

-Matches 0 or more times ``` Example: "ca*t" “ct” “cat” “caat” “caaat” “caaaat” ```

Question 32

+

Answer 32

-Matches 1 or more times ``` Example: "ca+t" “ct” (no match) “cat” “caat” “caaat” “caaaat” ```

Question 33

?

Answer 33

-Matches 0 or 1 times ``` Example: "ca?t" “ct” “cat” “caat” (no match) “caaat” (no match) “caaaat” (no match) ```

Question 34

{#,}

Answer 34

-Matches at least a specific number of times ``` Example: "ca{2,}t" “ct” (no match) “cat” (no match) “caat” “caaat” “caaaat” ```

Question 35

{# , #}

Answer 35

-Matches within a specific range of times ``` Example: "ca{2,3}t" “ct” (no match) “cat” (no match) “caat” “caaat” “caaaat” (no match) ```

Question 36

|

Answer 36

-Alteration: matches either the expression before or the expression after (OR) Example: "cat|dog" “cat” “dog” “bird” (no match)

Question 37

^

Answer 37

-Start of the string ``` Example: "^cat" “cat” “catsup” “concatenate” (no match) “kitty-cat” (no match) ```

Question 38

$

Answer 38

-End of the string ``` Example: "cat$" “cat” “catsup” (no match) “concatenate” (no match) “kitty-cat” ```

Answer 39

Escape Character: escapes the next character to be treated as a literal character Example: /$ "$"

Question 40

( ... )

Answer 40

-Capture Group: identifies matches that should be extracted Example: "c(at)" “cat” (“at” is captured) “bat” (no match)

Question 41

(?: ... )

Answer 41

-Non-Capturing Group: identifies matches that should not be extracted Example: "c(?:at)" “cat” ("c" is captured) “bat” (no match)

Question 42

(?! ... )

Answer 42

-Negative Lookahead Group: identifies expressions that negate earlier matches Example: "cat(?! burglar)" “cat” “cats” “cat burglar” (no match)