PHP 함수 및 클래스에 대한 심층 분석

function greet($name) { echo "Hello, $name!"; } greet('John'); // 输出：Hello, John!

function add($x, $y) { $x += $y; // 按值传递，不会修改原变量 return $x; } $a = 10; $b = add($a, 5); // $b 为 15，$a 仍然为 10 function swap(&$x, &$y) { $temp = $x; $x = $y; $y = $temp; // 按引用传递，交换原变量的值 } $a = 10; $b = 5; swap($a, $b); // $a 为 5，$b 为 10

class Person { public $name; public $age; public function __construct($name, $age) { $this->name = $name; $this->age = $age; } public function greet() { echo "Hello, my name is {$this->name} and I am {$this->age} years old."; } } $person = new Person('John', 30); $person->greet(); // 输出：Hello, my name is John and I am 30 years old.

class Employee extends Person { public $salary; public function __construct($name, $age, $salary) { parent::__construct($name, $age); $this->salary = $salary; } public function greet() { parent::greet(); echo " I earn \$" . $this->salary . " per year."; } } $employee = new Employee('John', 30, 50000); $employee->greet(); // 输出：Hello, my name is John and I am 30 years old. I earn $50000 per year.

function register($username, $password, $email) { // 验证参数 // ... // 创建用户对象 $user = new User($username, $password, $email); // 保存用户到数据库 // ... // 返回用户对象 return $user; }

class User { public $username; public $password; public $email; public function __construct($username, $password, $email) { $this->username = $username; $this->password = $password; $this->email = $email; } }

$username = 'John'; $password = 'password'; $email = 'john@example.com'; $user = register($username, $password, $email); // ...