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Type restrictions for PHP function parametersApr 19, 2024 pm 03:18 PM
phpiterable objectcode readabilityType restrictions

PHP function parameters can specify type restrictions to limit the function to only receive specific types of data, including: bool, int, float, string, array, object, callable, iterable. This restriction improves code readability and maintainability, and prevents arguments of mismatched types by raising a TypeError exception.

PHP 函数参数的类型限制

Type restrictions of PHP function parameters

In PHP, you can specify type restrictions for function parameters to limit the functions that can only Receive data of a specific type. This helps improve code readability and maintainability.

Syntax

function functionName(type $paramName) {
    // ...
}

Type

PHP supports the following types:

  • bool: Boolean value
  • int: Integer
  • float: Floating point number
  • string: String
  • array: Array
  • object: Object
  • callable: Anonymous Function or closure
  • iterable: any iterable object (such as array, object)

Practical case

The following is a function that verifies the user's email address:

function validateEmail(string $email): bool {
    return filter_var($email, FILTER_VALIDATE_EMAIL);
}

This function can only accept string parameters and performs email verification on them. If the argument provided is not a string, a TypeError exception will be raised.

Notes

  • Type qualifiers are optional. If not specified, the function will accept any type of data.
  • Type restrictions can only be used in function definitions. Cannot specify type in function call.
  • If the provided parameters do not match the specified type, a TypeError exception will be raised.
  • You can use union types (such as string|int) to specify that the function can accept multiple types.
  • It is recommended to use type restrictions when possible to improve code reliability and debuggability.

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