match
(PHP 8)
The match expression branches evaluation based on an
identity check of a value.
Similarly to a switch statement, a
match expression has a subject expression that is
compared against multiple alternatives. Unlike switch,
it will evaluate to a value much like ternary expressions.
Unlike switch, the comparison is an identity check
(===) rather than a weak equality check (==).
Match expressions are available as of PHP 8.0.0.
Example #1 Structure of a match expression
<?php
$return_value = match (subject_expression) {
single_conditional_expression => return_expression,
conditional_expression1, conditional_expression2 => return_expression,
};
?>
Example #2 Basic match usage
<?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);
?>
The above example will output:
string(19) "This food is a cake"
Note: The result of a
matchexpression does not need to be used.
Note: A
matchexpression must be terminated by a semicolon;.
The match expression is similar to a
switch statement but has some key differences:
-
A
matcharm compares values strictly (===) instead of loosely as the switch statement does. -
A
matchexpression returns a value. -
matcharms do not fall-through to later cases the wayswitchstatements do. -
A
matchexpression must be exhaustive.
As switch statements, match
expressions are executed match arm by match arm.
In the beginning, no code is executed.
The conditional expressions are only evaluated if all previous conditional
expressions failed to match the subject expression.
Only the return expression corresponding to the matching conditional
expression will be evaluated.
For example:
<?php
$result = match ($x) {
foo() => ...,
$this->bar() => ..., // $this->bar() isn't called if foo() === $x
$this->baz => beep(), // beep() isn't called unless $x === $this->baz
// etc.
};
?>
match expression arms may contain multiple expressions
separated by a comma. That is a logical OR, and is a short-hand for multiple
match arms with the same right-hand side.
<?php
$result = match ($x) {
// This match arm:
$a, $b, $c => 5,
// Is equivalent to these three match arms:
$a => 5,
$b => 5,
$c => 5,
};
?>
A special case is the default pattern.
This pattern matches anything that wasn't previously matched.
For example:
<?php
$expressionResult = match ($condition) {
1, 2 => foo(),
3, 4 => bar(),
default => baz(),
};
?>
Note: Multiple default patterns will raise a
E_FATAL_ERRORerror.
A match expression must be exhaustive. If the
subject expression is not handled by any match arm an
UnhandledMatchError is thrown.
Example #3 Example of an unhandled match expression
<?php
$condition = 5;
try {
match ($condition) {
1, 2 => foo(),
3, 4 => bar(),
};
} catch (\UnhandledMatchError $e) {
var_dump($e);
}
?>
The above example will output:
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
}
Using match expressions to handle non identity checks
It is possible to use a match expression to handle
non-identity conditional cases by using true as the subject
expression.
Example #4 Using a generalized match expressions to branch on integer ranges
<?php
$age = 23;
$result = match (true) {
$age >= 65 => 'senior',
$age >= 25 => 'adult',
$age >= 18 => 'young adult',
default => 'kid',
};
var_dump($result);
?>
The above example will output:
string(11) "young adult"
Example #5 Using a generalized match expressions to branch on string content
<?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);
?>
The above example will output:
string(2) "fr"
