my $foo="regexp";
my @matches = $foo =~ /(re)ge(xp)/;

#and

my $regex=qr{(re)ge(xp)};
my @matches = $foo =~ $regex;


##</code><code>##

> perl -we'use strict;use P;
my $regex=qr{(re)ge(xp)};
my @matches0 = "regexpregexp" =~ /(re)ge(xp)/g;
my @matches = "regexpregexp" =~ $regex;
my @matches1 = "regexpregexp" =~ /$regex/g;
P "matches=%s, 0=%s, 1=%s", \@matches, \@matches0, \@matches1; 
'
matches=["re", "xp"], 0=["re", "xp", "re", "xp"], 1=["re", "xp", "re", "xp"]