PHP CASE 语句不适用于零值

PHP CASE statement not working with ZERO values(PHP CASE 语句不适用于零值)

问题描述

我不明白这里发生了什么.从逻辑上讲，这对我来说没有任何意义.

I don't understand what's happening here. Logically, it doesn't make any sense to me.

<?php
$level = 0;

switch ($level) {

  case $level > 80: $answer = 'high'; break;
  case $level > 60: $answer = 'moderate-to-high'; break;
  case $level > 40: $answer = 'moderate'; break;
  case $level > 20: $answer = 'low-to-moderate'; break;
  default: $answer = 'low'; break;
}   
echo $answer;
?>

当 $level == 0 时，返回high".这对我来说没有任何意义.有人可以解释这里发生了什么吗?

When $level == 0, it returns "high". This doesn't make any sense to me. Can someone explain what's happening here?

推荐答案

将 switch ($level) 改为 switch (true) 即可.

switch 语句执行相等性测试关于案例中的价值观.PHP 正在评估您的 > 比较，所以 case $level >80 变为 case false.false 被认为等于 0，所以第一种情况匹配.

switch statements perform equality tests on the values in the cases. PHP is evaluating your > comparisons, so case $level > 80 becomes case false. false is considered to be equal to 0, so the first case matches.

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