Do you put objects in php arrays?

In PHP, arrays can store different types of data, including strings, numbers, Boolean, and objects. Objects stored in arrays are a very interesting problem because if we store an object in an array, we can easily use arrays to manage and manipulate collections of these objects. However, objects are stateful in memory, while arrays are stateless, so we need to consider how to store objects in arrays and how to use them correctly.

First of all, you can store the object in an array. The object here refers to the instantiation object of the class, that is, the object created through the new keyword. For example, define a Person class and then create two objects:

class Person {
    public $name;
    public $age;
}

$p1 = new Person();
$p1->name = 'Tom';
$p1->age = 20;

$p2 = new Person();
$p2->name = 'John';
$p2->age = 30;

$persons = [$p1, $p2];

By storing the $p1 and $p2 objects in the array $persons, we can easily iterate through each of the arrays with a foreach loop Object, like this:

foreach ($persons as $p) {
    echo $p->name . ' is ' . $p->age . ' years old.';
}

In the same way, we can use for loop, while loop, etc. to traverse the objects in the array.

However, it is important to note that there are some subtle differences in storing objects in arrays. In PHP 5, objects in arrays are passed by reference, which means that if we change the properties of an object in the array, the original object will also be modified. For example:

$p = new Person();
$p->name = 'Tom';
$p->age = 20;

$persons = [$p];

$persons[0]->name = 'John';

echo $p->name;  // 输出 John

Here the object $p stored in the $persons array, after modifying the $p object properties in the $persons array, the original $p object is also modified.

In PHP 7, objects in arrays are passed by value, which is different from PHP 5. This means that when modifying object properties in the array, the original object is not modified. For example:

$p = new Person();
$p->name = 'Tom';
$p->age = 20;

$persons = [$p];

$persons[0]->name = 'John';

echo $p->name;  // 输出 Tom

The object $p stored in the $persons array here, after modifying the $p object properties in the $persons array, the original $p object has not been modified.

Therefore, when using an array to store objects, we need to clearly know whether the object is passed by value or by reference. If passing by reference, we need to note that when modifying the objects in the array, the original object may be modified. If we pass by value, we can modify the object stored in the array according to our needs without affecting the original object.

In short, we can use arrays to store objects, so that we can easily manage and operate collections of objects. It is important to note that the objects stored in the array are passed by value or by reference, and we need to consider this to use the objects in the array correctly.

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