?
or \?
)
If the syntax bit RE_LIMITED_OPS
is set, then Regex doesn't
recognize this operator. Otherwise, if the syntax bit
RE_BK_PLUS_QM
isn't set, then ?
represents this operator;
if it is, then \?
does.
This operator is similar to the match-zero-or-more operator except that it repeats the preceding regular expression once or not at all; see Match-zero-or-more Operator, to see what it operates on, how some syntax bits affect it, and how Regex backtracks to match it.
For example, supposing that ?
represents the match-zero-or-one
operator; then ca?r
matches both car
and cr
, but
nothing else.