regex101: PCRE (Legacy) Match Workspace

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive)

Non-Capturing Group(?:(?(1)(?!)|(a))|(?(2)(?!)|(b))|.){0,10}?

{0,10}?repeats the group contents below between 0 and 10 times:

1st Alternative(?(1)(?!)|(a))

Condition(?(1)(?!)|(a))

Uses the first branch if group 1 matched

If the condition is true, match this branch:(?!)

Negative Lookahead(?!) — always fails to match

Otherwise, match this branch:(a)

Group 1(a)

athe literal a (97₁₀ / 141₈ / 61₁₆) (case sensitive)

2nd Alternative(?(2)(?!)|(b))

Condition(?(2)(?!)|(b))

Uses the first branch if group 2 matched

If the condition is true, match this branch:(?!)

Negative Lookahead(?!) — always fails to match

Otherwise, match this branch:(b)

Group 2(b)

bthe literal b (98₁₀ / 142₈ / 62₁₆) (case sensitive)

3rd Alternative.

.any character (except for line terminators)

ythe literal y (121₁₀ / 171₈ / 79₁₆) (case sensitive)

Condition(?(1)|(?!))

Uses the first branch if group 1 matched

If the condition is true, match this branch: — matches an empty string

Otherwise, match this branch:(?!)

Negative Lookahead(?!) — always fails to match

Condition(?(2)|(?!))

Uses the first branch if group 2 matched

If the condition is true, match this branch: — matches an empty string

Otherwise, match this branch:(?!)

Negative Lookahead(?!) — always fails to match

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

x(?:(?(1)(?!)|(a))|(?(2)(?!)|(b))|.){0,10}?y(?(1)|(?!))(?(2)|(?!))

New

Match:
...x12a456b89y... ...x12a456b89y... 
...xaabbaabby...
x...a.y.b...y  (there are 11 chars between x and y, no match is correct!)
...x..a...b..y...
...x..b...a..y...
...x..a...b..y...a...
...x..a...b..y...b...
...x..a...b..y...y...
...x..a.x.b..y...
...x..a.y.b..y...
...xaabbaabbay...
...x..a...b..y... ...x..a...b..y... (2 matches)
...xaby...xaby... (2 matches)

Don't match:
...x..a...b......
...x......b..y...
...x..a......y...
...x..a...b......y...
...x......b..y...a...
...x..a......y...b...
...x..a.y.b......
...x..a.y.b......y...
...x..a.y.b.x....y...
.a.x......b..y...
.b.x..a......y...
x...y...a...b

Regular Expressions 101

Regular Expression

Extraction