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Master the analysis of the underlying development principles of PHP8 and application examples of new features
function add(int $a, int $b): int { return $a + $b; }
In the above code, the types of the parameters $a and $b of the function add are annotated as int, and the type of the return value is also annotated as int. In this way, if the parameter type passed in is incorrect, PHP8 will report an error.
3.2. Attribute visibility identifier
PHP8 provides support for attribute visibility identifiers. Developers can use the public, protected, and private keywords to limit the visibility of properties. This can effectively control attribute access permissions and improve code encapsulation. The following is an example:
class Person { public string $name; protected int $age; private string $address; }
In the above code, the attribute $name is marked as public and can be directly accessed outside the class; the attribute $age is marked as protected and can only be accessed inside the class and subclasses. Access; the property $address is marked private and can only be accessed within the class.
3.3. Persistent construction properties
PHP8 introduces persistent properties that can be defined outside the constructor. The values of these properties persist throughout the object's lifetime. The following is an example:
class Counter { private int $count = 0; public function increment(): void { $this->count++; } public function getCount(): int { return $this->count; } } $counter = new Counter(); $counter->increment(); echo $counter->getCount(); // 输出1
In the above code, class Counter defines a property $count and initializes it to 0. Each time the increment method is called, the value of the attribute $count will be increased by 1. By calling the getCount method, the current value of the attribute $count can be obtained.
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