XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (609 page)

is
b#
. If you want to match the shortest possible substring, add a
?
after the quantifier to make it non-greedy:
replace(“banana”, “(an)+?a”, “#”)
is
b#na
. Note that the final three characters of
banana
don't result in a replacement, because two matches never overlap: the middle
a
cannot participate in two different matching substrings.

Another situation that can cause two different substrings to match at the same position is where the regex contains two alternatives that both match. For example, the regex
a|ana
could match the second character of
banana
, or it could match characters 2 to 4. The rule here is that the first (leftmost) alternative wins. So the result of
replace(“banana”, “a|ana”, “#”)
is
b#n#n#
, whereas the result of
replace(“banana”, “ana|a”, “#”)
is
b#n#
.