如何在PHP中设置Cookie

Question

嗨，我正在按照W3schools的示例在PHP中设置cookie，这表明未设置cookie。有什么办法吗？全部

<?php
if(!'isset'($_COOKIE[$cookie_name])) {
    echo "Cookie named '" . $cookie_name . "' is not set!";
} else {
    echo "Cookie '" . $cookie_name . "' is set!";
    echo "Value is: " . $_COOKIE[$cookie_name];
}
?>