PHP8 の新機能を明らかにする: 基礎となる開発原則をマスターし、実際のプロジェクトに適用する

function fib($n) {
    if ($n <= 1) {
        return $n;
    }
    return fib($n - 1) + fib($n - 2);
}

echo fib(10); // 输出：55

class User {
    public string $name;
    public int $age;
    
    public function __construct(string $name, int $age) {
        $this->name = $name;
        $this->age = $age;
    }
    
    public function getProfile(): string {
        return "Name: {$this->name}, Age: {$this->age}";
    }
}

$user = new User("John Doe", 25);
echo $user->getProfile(); // 输出：Name: John Doe, Age: 25

class Shape {
    protected float|int $length;
}

class Circle extends Shape {
    protected float $radius;
    
    public function __construct(float $radius) {
        $this->radius = $radius;
    }
}

class Square extends Shape {
    protected int $side;
    
    public function __construct(int $side) {
        $this->side = $side;
    }
}

function getArea(Shape $shape): float|int {
    if ($shape instanceof Circle) {
        return 3.14 * $shape->radius * $shape->radius;
    } elseif ($shape instanceof Square) {
        return $shape->side * $shape->side;
    }
    
    return 0;
}

$circle = new Circle(5);
echo getArea($circle); // 输出：78.5

$square = new Square(5);
echo getArea($square); // 输出：25

function calculate(string $operator, int $a, int $b): float|int {
    return match ($operator) {
        "+" => $a + $b,
        "-" => $a - $b,
        "*" => $a * $b,
        "/" => $a / $b,
        default => throw new Exception("Unsupported operator"),
    };
}

echo calculate("+", 5, 3); // 输出：8