程嶏清单7-17.txt

< linux网络编程工具>>配套源码

$x = 'Perl is free.';
$y = 'ManagerWare costs $99.95.';
foreach ($x, $y) {
    /^(\w+) (?:is|(costs)) (?(2)(\$\d+)|\w+)/;  # Either (\$\d+) or \w+
    if ($3) {
        print "$1 costs money.\n";         # ManagerWare costs money.
    } else {
        print "$1 doesn't cost money.\n";  # Perl doesn't cost money.
    }
}