A brief analysis of several types of php arrays

PHP is an object-oriented programming language widely used in web development. In PHP, array is a very important data type and can be simply understood as a collection of data of the same type. In this article, we will discuss how many arrays are there in PHP.

In PHP, array is a basic data type used to store data collections. According to data type, PHP arrays can be divided into the following types:

1. Index array

Index array is the most common array type in PHP. It uses a set of numbers as keys for array elements, with the numbers starting from 0 and increasing one by one. For example:

$array = array("apple", "banana", "orange");

In the above example, $array is an index array, containing three elements, using the numbers 0, 1, and 2 as keys respectively, corresponding to "apple" The values ​​of the three elements ", "banana", and "orange".

2. Associative array

Associative array is also a widely used array type. Compared with index arrays, associative arrays use strings as keys for array elements, which can represent some key-value pairs more intuitively. For example:

$age = array("Peter" => 35, "Ben" => 37, "Joe" => 43);

In the above example, $age is an associative array with the key name being a string and the value being an integer. Through $age["Peter"], you can get the value with the key "Peter", which is 35.

3. Multidimensional array

Multidimensional array refers to storing another array in one array. In PHP, multi-dimensional arrays can be infinitely nested to form extremely flexible data structures. For example:

$products = array(
    array("name" => "apple", "price" => 10),
    array("name" => "banana", "price" => 20),
    array("name" => "orange", "price" => 15),
);

In the above example, $products is an array containing 3 elements, and each element is an array, including "name" and "price" The value of both keys.

How many PHP arrays are there? This question is not easy to answer. Because the length of arrays in PHP is dynamic, it constantly changes as the array expands and contracts. However, we can obtain the length and other information of the array through a series of functions:

1. count()Function

count( )Function is used to get the number of elements in the array. For example:

$array = array("apple", "banana", "orange");
echo count($array); // 输出 3

In the above example, using the count() function you can get the length of the $array array to be 3, that is, 3 elements.

2. sizeof()function

##sizeof()function and count()function The function is basically the same and can also be used to obtain the array length. For example:

$array = array("apple", "banana", "orange");
echo sizeof($array); // 输出 3

Using the

sizeof() function, you can also get the length of the $array array to be 3.

3. $array.lengthProperty

In some other programming languages, the way to get the length of an array may be to directly read the length property of the array , this method can also be used in PHP, but you need to use the

count() function, for example:

$array = array("apple", "banana", "orange");
echo $array.length; // 报错
echo count($array); // 输出 3

In the above example, since the length attribute of the array does not exist in PHP, you can directly Using

$array.length will result in a syntax error. The correct way is to use the count() function.

To sum up, the length of a PHP array can be obtained through the

count() function, the sizeof() function or by traversing the array. The array type includes index Arrays, associative arrays and multi-dimensional arrays, among which multi-dimensional arrays can be infinitely nested to form complex data structures. For PHP programming, mastering the use of arrays is a very important part.

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