Regular expressions are used several ways in Perl. They’re used in conditionals to determine whether a string matches a particular pattern. They’re also used to find patterns in strings and replace the match with something else.
The ordinary pattern match operator looks like /
pattern
/
. It matches against the $_
variable by default. If the pattern is
found in the string, the operator returns true (1
); if there is no match, a false value (“”)
is returned.
The substitution operator looks like s/
pattern
/
replace
/
. This operator searches $_
by default. If it finds the specified
pattern
, it is replaced with the string in
replace
. If
pattern
is not matched, nothing
happens.
You may specify a variable other than $_
with the =~
binding operator (or the negated !~
binding operator, which returns true if
the pattern is not matched). For example:
$text =~ /sampo/;
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