PHP 中的条件 switch 语句

发布于 2024-12-10 17:27:09 字数 424 浏览 1 评论 0原文

我已经习惯了 vb.net 的 Select Case 语法本质上是一个 switch 语句，您可以在其中执行诸如 Case Is > 之类的操作5 如果匹配，它将执行该案例。

由于我不知道 PHP 中的实际名称，我该如何做我将称之为“条件 switch 语句”的事情呢？

或者，有什么快速的方法来管理这个问题？

switch($test)
{
    case < 0.1:
        // do stuff
        break;
}

这就是我目前尝试过的。

原文

I'm quite used to vb.net's Select Case syntax which is essentially a switch statement, where you can do things like Case Is > 5 and if it matches, it will execute that case.

How can I do what I'm going to call "conditional switch statements" since I don't know the actual name, in PHP?

Or, what's a quick way to manage this?

switch($test)
{
    case < 0.1:
        // do stuff
        break;
}

That's what I've tried currently.

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

鞋纸虽美，但不合脚ㄋ〞 2024-12-17 17:27:09

我认为您正在寻找类似的东西（这不完全是您想要的，或者至少我理解是您的需要）。

switch (true) 查找计算结果为真值的情况，并执行其中的代码，直到第一次中断；它遇到。

<?php

switch (true) {

case ($totaltime <= 1):
echo "That was fast!";
break;

case ($totaltime <= 5):
echo "Not fast!";
break;

case ($totaltime <= 10):
echo "That's slooooow";
break;
}

?>

I think you're searching for something like this (this is not exactly what you want or at least what I understand is your need).

switch (true) finds the cases which evaluate to a truthy value, and execute the code within until the first break; it encounters.

<?php

switch (true) {

case ($totaltime <= 1):
echo "That was fast!";
break;

case ($totaltime <= 5):
echo "Not fast!";
break;

case ($totaltime <= 10):
echo "That's slooooow";
break;
}

?>

回复收藏 0 原文

木有鱼丸 2024-12-17 17:27:09

我试图将其添加为 BoltCock 答案的评论，但 SO 告诉我他的答案已锁定，因此我将其作为一个单独的（本质上是多余的）答案：

BoltCock 的“switch(true)”答案是很像以下示例，虽然逻辑上等同于 if + else if + else 可以说更漂亮，因为条件表达式是垂直对齐的，并且是 PHP 中的标准/可接受的做法。

但是 if + else if + else 语法本质上是跨脚本语言通用的，因此任何人都可以立即读取（并且可维护），这也让我点头。

回复收藏 0 原文

桃气十足 2024-12-17 17:27:09

在 PHP 8.0+ 中，还有另一种方法可以实现此目的，即使用

如果每种情况下都有一个表达式，则它相当于以下 match 语句。请注意，与 switch 语句不同，我们可以选择返回一个变量（在此代码中，我将结果存储在 $result 中）。

$test = 0.05;
$result = match (true) {
    $test < 0.1 => "I'm less than 0.1",
    $test < 0.01 => "I'm less than 0.01",
    default => "default",
};

var_dump($result);

Match 语句只允许您在每个条件后面有一个表达式。您可以通过调用函数来解决此限制。

function tinyCase(){}
function veryTinyCase(){}
function defaultCase(){}

$test = 0.01;
match (true) {
    $test < 0.1 => tinyCase(),
    $test < 0.01 => veryTinyCase(),
    default => defaultCase(),
};

作为参考，如果您只想检查相等性，可以执行以下操作：

$result = match ($test) { // This example shows doing something other than match(true)
    0.1 => "I'm equal to 0.1",
    0.01 => "I'm equal to 0.01",
    default => "default",
};

Match 语句确实与 switch 语句有一些关键区别，您需要注意：

我的最后一个示例将使用严格的相等性检查 ===< /code> 而不是松散的 ==。
如果未提供默认情况，则在没有匹配项时会引发 UnhandledMatchError 错误。
如果您忘记添加 break，也不用担心会陷入下一种情况。

There is an additional way you can accomplish this, in PHP 8.0+, by using a match statement.

If you have a single expression within each case, it is equivalent to the following match statement. Note that unlike switch statements, we can choose to return a variable (in this code I am storing the result in $result).

$test = 0.05;
$result = match (true) {
    $test < 0.1 => "I'm less than 0.1",
    $test < 0.01 => "I'm less than 0.01",
    default => "default",
};

var_dump($result);

Match statements only allow you to have a single expression after each condition. You can work around this limitation by calling a function.

function tinyCase(){}
function veryTinyCase(){}
function defaultCase(){}

$test = 0.01;
match (true) {
    $test < 0.1 => tinyCase(),
    $test < 0.01 => veryTinyCase(),
    default => defaultCase(),
};

And for reference, if you just want to check for equality you can do:

$result = match ($test) { // This example shows doing something other than match(true)
    0.1 => "I'm equal to 0.1",
    0.01 => "I'm equal to 0.01",
    default => "default",
};

Match statements do have some key differences from switch statements that you need to watch out for:

My last example will use a strict equality check === instead of a loose one ==.
If a default case is not provided, an UnhandledMatchError error is thrown when nothing matches.
And there is no worrying about falling through to the next case if you forget to add break.

回复收藏 0 原文

我的影子我的梦 2024-12-17 17:27:09

带条件的 switch 语句

switch(true)
{
    case ($car == "Audi" || $car == "Mercedes"):
        echo "German cars are amazing";
        break;
    case ($car == "Jaguar"):
        echo "Jaguar is the best";
        break;
    default:
        echo "$car is Ok";
}

Switch statement with conditions

switch(true)
{
    case ($car == "Audi" || $car == "Mercedes"):
        echo "German cars are amazing";
        break;
    case ($car == "Jaguar"):
        echo "Jaguar is the best";
        break;
    default:
        echo "$car is Ok";
}

回复收藏 0 原文