Regular Expressions 101

Group 1(x+x+)+

+repeats the group contents below at least once:

x+the literal x (120₁₀ / 170₈ / 78₁₆) (case sensitive), repeated at least once

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

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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(x+x+)+y

New


xxxxxxxxxxxxxxxx

Catastrophic backtracking example:

Note the pattern looks fairly simple, but it needs over 80000 steps to decide it is not a match.
With just 16 'x' it already takes a large amount of steps to finally decides it does not work.

(click "regex debugger" on the left to see details on steps taken)

See https://www.regular-expressions.info/catastrophic.html for more info.

Regular Expression

Extraction