$string = "foo bar";
@match = $string =~ m/(f(oo)) (b(ar))/
print "$match[0]\n";    # prints "foo" (captured by /(f(oo))/
print "$match[1]\n";    # prints "oo"  (captured by /(oo)/
print "$match[2]\n";    # prints "bar" (captured by /(b(ar))/
print "$match[3]\n";    # prints "ar" (captured by  /(ar)/