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PHP function parameter type strict checking can ensure that the passed parameters are consistent with the declared type. When enabled via declare(strict_types=1), function parameters are required to match the specified type, otherwise a TypeError exception is thrown. Strict checking supports basic types (int, float), composite types (objects, arrays), union types (int|string) and optional types (?int) to improve code robustness and prevent wrong type parameters from being passed.
PHP function parameter type checking refers to checking whether the actually passed parameter type is consistent with the function when the function is called. A procedure whose declared parameter types are consistent. The robustness of your code can be improved by strict checking to ensure that the parameters passed to the function are as expected.
In PHP 7.0 and above, you can use the Declare
statement to strictly check the function parameter type:
declare(strict_types=1); function add(int $a, int $b) {...}
Pass strict_types=1
After declaring that strict mode is enabled, function add
requires two integer type parameters to be passed in, otherwise a TypeError exception will be thrown.
PHP supports strict checking of the following basic types and composite types:
int
, float
, bool
, string
, null
or
Class
Scenario:
Define a functioncalculateArea to calculate the area of geometric figures. Different parameters need to be passed according to different graphics types:
function calculateArea($shape, $params) {...}
Use type checking to prevent parameter errors:
declare(strict_types=1); function calculateArea(string $shape, array $params): float {...}Declare and clarify through
strict_types Parameter types prevent passing parameters of the wrong type. For example:
calculateArea(123, []); // 抛出 TypeError 异常
Use union types to improve flexibility:
function calculateArea(string $shape, int|float $radius): float {...}Union types allow functions to receive different types of parameters according to different situations. For example, to calculate the area of a circle or square:
calculateArea('circle', 5); calculateArea('square', 10);Points to note
value, you can use the optional type
?.
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