简明条件"？"

Question

下面的第一个PHP脚本确实显示"正好七个",但另一个不显示.知道为什么吗？

---这一件作品---

<?
$num = 7;
echo ($num == 7) ? "exactly seven" : "not seven";
?>

---这个没有---

<?
$num = 7;
echo ($num == 7) ? "exactly seven" : ($num > 7) ? "more than seven" : "less than seven";
?>

Answer 1

它被称为运营商的优先权.添加一些括号以确保以正确的顺序发生事情,例如

$num = 7;
echo ($num == 7) ? "exactly seven" : (($num > 7) ? "more than seven" : "less than seven");