How to define function types and parameters in PHP?

In PHP, you can use type hints to define the type and parameters of a function: To define parameter types: Use a colon (:) and the type name after the parameter name. Supported types: int, float, string, bool, etc. Composite types: You can use a vertical bar (|) to indicate that a parameter can accept multiple possible types. Return value type: Use a colon (:) and the type name before the function name. Practical example: Type hints help ensure code accuracy and maintainability.

How to define the type and parameters of a function in PHP

In PHP, you can use type hints to define the parameter and return value types of a function. This helps ensure code accuracy and maintainability, and can be achieved by using PHP 7.0 or higher.

Define parameter types:

To define function parameter types, use a colon (:) and the type name after the parameter name:

function greet(string $name): void {}

In In the above example, the greet function accepts a $name parameter of type string and does not return a value (so the return type is void).

Supported types:

PHP supports the following type hints:

• Basic type: int , float, string, bool
• ##Empty type: null
• Array: array
• Callback: callable
• Class: ClassName (can be an interface or parent class)

Composite type:

You can use vertical bars (| ) represents a composite type, indicating that the parameter can accept multiple possible types:

function calculate(int|float $number) {}

Return value type:

To define the function return value type, use a colon before the function name (:) and type name:

function getFullName(): string {}

Practical example:

The following is a practical example of using type hints:

<?php

class Person
{
    private string $firstName;
    private string $lastName;

    public function __construct(string $firstName, string $lastName)
    {
        $this->firstName = $firstName;
        $this->lastName = $lastName;
    }

    public function getFullName(): string
    {
        return $this->firstName . ' ' . $this->lastName;
    }
}

function createPerson(string $firstName, string $lastName): Person
{
    return new Person($firstName, $lastName);
}

$person = createPerson('John', 'Doe');

echo $person->getFullName(); // 输出：John Doe

In this example , the constructor of the

Person class and the createPerson function all have type hints to ensure that the parameters passed to them and the returned values ​​have the correct types.

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