This will allow for a nicer FizzBuzz solution:
<?php
function fizzbuzz($num) {
print match (0) {
$num % 15 => "FizzBuzz" . PHP_EOL,
$num % 3 => "Fizz" . PHP_EOL,
$num % 5 => "Buzz" . PHP_EOL,
default => $num . PHP_EOL,
};
}
for ($i = 0; $i <=100; $i++)
{
fizzbuzz($i);
}
PHP - Manual: match
2024-12-23
match
(PHP 8)
match 表达式基于值的一致性进行分支计算。
match表达式和 switch 语句类似，
都有一个表达式主体，可以和多个可选项进行比较。
与 switch 不同点是，它会像三元表达式一样求值。
与 switch 另一个不同点，它的比较是严格比较（
===）而不是松散比较（==）。
Match 表达式从 PHP 8.0.0 起可用。
示例 #1 match 表达式结构
<?php
$return_value = match (subject_expression) {
single_conditional_expression => return_expression,
conditional_expression1, conditional_expression2 => return_expression,
};
?>
示例 #2 match 的基础用法
<?php
$food = 'cake';
$return_value = match ($food) {
'apple' => 'This food is an apple',
'bar' => 'This food is a bar',
'cake' => 'This food is a cake',
};
var_dump($return_value);
?>
以上例程会输出：
string(19) "This food is a cake"
注意: 不一定要使用
match表达式的结果。
注意:
match表达式必须使用分号;结尾。
match 表达式跟 switch 语句相似，但是有以下关键区别：
-
match比较分支值，使用了严格比较 (===)， 而 switch 语句使用了松散比较。 -
match表达式会返回一个值。 -
match的分支不会像switch语句一样， 落空时执行下个 case。 -
match表达式必须彻底列举所有情况。
match 表达式和 switch 语句类似，
逐个检测匹配分支。一开始不会执行代码。
只有在所有之前的条件不匹配主体表达式时，才会执行剩下的条件表达式。
只会执行返回的表达式所对应的匹配条件表达式。
举例：
<?php
$result = match ($x) {
foo() => ...,
$this->bar() => ..., // 如果 foo() === $x，不会执行 $this->bar()
$this->baz => beep(), // 只有 $x === $this->baz 时才会执行 beep()
// 等等
};
?>
match 表达式分支可以通过逗号分隔，包含多个表达式。
这是一个逻辑 OR，当多个分支表达式右侧相同时，就可以用这种缩写。
<?php
$result = match ($x) {
// 匹配分支：
$a, $b, $c => 5,
// 等同于以下三个分支：
$a => 5,
$b => 5,
$c => 5,
};
?>
default 模式是个特殊的条件。
当之前的条件都不匹配时，会匹配到该模式。
For example:
<?php
$expressionResult = match ($condition) {
1, 2 => foo(),
3, 4 => bar(),
default => baz(),
};
?>
注意: 多个 default 模式将会触发
E_FATAL_ERROR错误。
match 表达式必须详尽列出所有情况。
如果主体表达式不能被任意分支条件处理，
会抛出 UnhandledMatchError。
示例 #3 match 表达式存在未处理的示例
<?php
$condition = 5;
try {
match ($condition) {
1, 2 => foo(),
3, 4 => bar(),
};
} catch (\UnhandledMatchError $e) {
var_dump($e);
}
?>
以上例程会输出：
object(UnhandledMatchError)#1 (7) {
["message":protected]=>
string(33) "Unhandled match value of type int"
["string":"Error":private]=>
string(0) ""
["code":protected]=>
int(0)
["file":protected]=>
string(9) "/in/ICgGK"
["line":protected]=>
int(6)
["trace":"Error":private]=>
array(0) {
}
["previous":"Error":private]=>
NULL
}
使用 match 表达式处理非一致性检查
可以使用 match 表达式将 true
作为主项表达式来处理非一致性条件的情况。
示例 #4 针对整数范围，使用宽泛的表达式匹配分支
<?php
$age = 23;
$result = match (true) {
$age >= 65 => 'senior',
$age >= 25 => 'adult',
$age >= 18 => 'young adult',
default => 'kid',
};
var_dump($result);
?>
以上例程会输出：
string(11) "young adult"
示例 #5 针对字符串内容，使用宽泛的表达式匹配分支
<?php
$text = 'Bienvenue chez nous';
$result = match (true) {
str_contains($text, 'Welcome') || str_contains($text, 'Hello') => 'en',
str_contains($text, 'Bienvenue') || str_contains($text, 'Bonjour') => 'fr',
// ...
};
var_dump($result);
?>
以上例程会输出：
string(2) "fr"
add a note
User Contributed Notes 7 notes
darius dot restivan at gmail dot com ¶
1 year ago
Hayley Watson ¶
1 year ago
As well as being similar to a switch, match expressions can be thought of as enhanced lookup tables — for when a simple array lookup isn't enough without extra handling of edge cases, but a full switch statement would be overweight.
For a familiar example, the following
<?php
function days_in_month(string $month): int
{
static $lookup = [
'jan' => 31,
'feb' => 0,
'mar' => 31,
'apr' => 30,
'may' => 31,
'jun' => 30,
'jul' => 31,
'aug' => 31,
'sep' => 30,
'oct' => 31,
'nov' => 30,
'dec' => 31
];
$name = strtolower(substr($name, 0, 3));
if(isset($lookup[$name])) {
if($name == 'feb') {
return is_leap($year) ? 29 : 28;
} else {
return $lookup[$name];
}
}
throw new InvalidArgumentException("Bogus month");
}
?>
with the fiddly stuff at the end, can be replaced by
<?php
function days_in_month(string $month): int
{
return match(strtolower(substr($month, 0, 3))) {
'jan' => 31,
'feb' => is_leap($year) ? 29 : 28,
'mar' => 31,
'apr' => 30,
'may' => 31,
'jun' => 30,
'jul' => 31,
'aug' => 31,
'sep' => 30,
'oct' => 31,
'nov' => 30,
'dec' => 31,
default => throw new InvalidArgumentException("Bogus month"),
};
}
?>
Which also takes advantage of "throw" being handled as of PHP 8.0 as an expression instead of a statement.
Anonymous ¶
9 months ago
<?php
function days_in_month(string $month, $year): int
{
return match(strtolower(substr($month, 0, 3))) {
'jan' => 31,
'feb' => is_leap($year) ? 29 : 28,
'mar' => 31,
'apr' => 30,
'may' => 31,
'jun' => 30,
'jul' => 31,
'aug' => 31,
'sep' => 30,
'oct' => 31,
'nov' => 30,
'dec' => 31,
default => throw new InvalidArgumentException("Bogus month"),
};
}
?>
can be more concisely written as
<?php
function days_in_month(string $month, $year): int
{
return match(strtolower(substr($month, 0, 3))) {
'apr', 'jun', 'sep', 'nov' => 30,
'jan', 'mar', 'may', 'jul', 'aug', 'oct', 'dec' => 31,
'feb' => is_leap($year) ? 29 : 28,
default => throw new InvalidArgumentException("Bogus month"),
};
}
?>
php at joren dot dev ¶
3 months ago
If you want to execute multiple return expressions when matching a conditional expression, you can do so by stating all return expressions inside an array.
<?php
$countries = ['Belgium', 'Netherlands'];
$spoken_languages = [
'Dutch' => false,
'French' => false,
'German' => false,
'English' => false,
];
foreach ($countries as $country) {
match($country) {
'Belgium' => [
$spoken_languages['Dutch'] = true,
$spoken_languages['French'] = true,
$spoken_languages['German'] = true,
],
'Netherlands' => $spoken_languages['Dutch'] = true,
'Germany' => $spoken_languages['German'] = true,
'United Kingdom' => $spoken_languages['English'] = true,
};
}
var_export($spoken_languages);
// array ( 'Dutch' => true, 'French' => true, 'German' => true, 'English' => false, )
?>
tm ¶
7 months ago
If you are using a match expression for non-identity checks as described above make sure whatever you are using is actually returning `true` on success.
Quite often you rely on truthy vs. falsy when using if conditions and that will not work for match (for example `preg_match`). Casting to bool will solve this issue.
mark at manngo dot net ¶
4 months ago
While you can’t polyfill a language construct, you can mimic the basic behaviour with a simple array.
Using example 2 above:
<?php
$food = 'apple';
$return_value = match ($food) {
'apple' => 'This food is an apple',
'bar' => 'This food is a bar',
'cake' => 'This food is a cake',
};
print $return_value;
?>
… you can get something similar with:
<?php
$food = 'apple';
$return_value = [
'apple' => 'This food is an apple',
'bar' => 'This food is a bar',
'cake' => 'This food is a cake',
][$food];
print $return_value;
?>
manoj904378 at gmail dot com ¶
5 months ago
When & Where should you use? that's most important part of match
<?php
$Error_Code=(int) 400;
$message=(string) match($Error_Code){
200=>"OK",
400=>"Bad Request",
401=>"Unauthorized",
403=>"Forbidden",
404=>"Not Found",
default=>"Unknown Error"
};
var_dump($message); // string(11) "Bad Request"
?>
官方地址：https://www.php.net/manual/en/control-structures.match.php
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