What are the classifications of php arrays

In PHP, array is a very common and useful data type. It can help us store and process large amounts of data, such as numbers, strings, objects, etc. When using arrays, it is also very important to understand the classification of arrays, because different types of arrays have different characteristics and uses. This article will introduce the four categories of arrays in PHP, namely index arrays, associative arrays, multidimensional arrays and object arrays.

1. Index array

Index array is the most common array type and the simplest one. The elements in the index array are ordered, and each element has a corresponding index value. In PHP, you can use subscripts to access and manipulate elements in an array. Subscripts are usually numeric types, starting from 0 and increasing.

For example, the following code demonstrates how to create and manipulate an indexed array:

// 创建索引数组
$numbers = array(1, 2, 3, 4, 5);

// 访问数组中的元素
echo $numbers[0]; // 输出 1

// 修改数组中的元素
$numbers[1] = 10;

// 遍历数组中的元素
foreach ($numbers as $number) {
    echo $number;
}

2. Associative array

Associative array is another common type of array Type, unlike indexed arrays, each element in an associative array has a unique key value. This key can be any legal PHP string. When working with associative arrays, you can use key values ​​to access and manipulate elements in the array.

For example, the following code demonstrates how to create and manipulate an associative array:

// 创建关联数组
$person = array(
    'name' => 'John',
    'age' => 30,
    'gender' => 'male'
);

// 访问数组中的元素
echo $person['name']; // 输出 John

// 修改数组中的元素
$person['age'] = 35;

// 遍历数组中的元素
foreach ($person as $key => $value) {
    echo $key . ': ' . $value;
}

3. Multidimensional array

A multidimensional array is an array that contains other arrays as an array of its elements. In PHP, you can create multidimensional arrays using any type of array, including indexed arrays, associative arrays, and other multidimensional arrays. Using multidimensional arrays can help us better organize and manipulate complex data structures.

For example, the following code demonstrates how to create and manipulate multidimensional arrays:

// 创建多维数组
$students = array(
    array('name' => 'John', 'age' => 20),
    array('name' => 'Sara', 'age' => 22),
    array('name' => 'Tom', 'age' => 18)
);

// 访问数组中的元素
echo $students[0]['name']; // 输出 John

// 修改数组中的元素
$students[1]['age'] = 23;

// 遍历数组中的元素
foreach ($students as $student) {
    echo $student['name'] . ': ' . $student['age'];
}

4. Object array

An object array contains objects as its elements array. In PHP, an object is a special data type with its own properties and methods. You can use object arrays to store and manipulate multiple objects.

For example, the following code demonstrates how to create and manipulate an array of objects:

// 创建对象数组
class Person {
    public $name;
    public $age;

    public function __construct($name, $age) {
        $this->name = $name;
        $this->age = $age;
    }
}

$people = array(
    new Person('John', 20),
    new Person('Sara', 22),
    new Person('Tom', 18)
);

// 访问数组中的元素
echo $people[0]->name; // 输出 John

// 修改数组中的元素
$people[1]->age = 23;

// 遍历数组中的元素
foreach ($people as $person) {
    echo $person->name . ': ' . $person->age;
}

Summary

In PHP, arrays are a very common and useful data type. Understanding the different types of arrays can help us better handle and manipulate data. This article introduces four categories of arrays in PHP, including indexed arrays, associative arrays, multidimensional arrays, and object arrays. I hope this article can help you better understand and apply arrays in PHP.

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