Regex

Question 1

.[{()*+?|^$

Answer 1

All characters match themselves except for these special characters.

Answer 2

Character match the start of a line.

Question 3

$

Answer 3

Character match the end of a line.

Question 4

(?:ab)+

Answer 4

Will repeat ‘ab’ without splitting out any separate sub-expressions.

Question 5

*, +, ?, and {}

Answer 5

Repeats operators.

Question 6

*

Answer 6

The operator will match the preceding atom zero or more times, for example the expression ab will match any of the following:

b
ab
aaaaaaaab

Question 7

+

Answer 7

{1,}

The + operator will match the preceding atom one or more times, for example the expression a+b will match any of the following:
ab
aaaaaaaab but will not match: b

Question 8

?

Answer 8

The ? operator will match the preceding atom zero or one times, for example the expression ca?b will match any of the following:
cb
cab

But will not match: caab

Question 9

a{n}

Answer 9

Matches ‘a’ repeated exactly n times.

Question 10

a{n,}

Answer 10

Matches ‘a’ repeated n or more times.

Question 11

a{n, m}

Answer 11

Matches ‘a’ repeated between n and m times inclusive.