PHP arrays are divided into several types of arrays by type

php arrays are divided into four types of arrays by type, namely: 1. Indexed Arrays; 2. Associative Arrays; 3. Multidimensional Arrays; 4. Constant Arrays (Constant Arrays).

The operating environment of this tutorial: windows10 system, php8.1.3 version, DELL G3 computer.

In the PHP programming language, array is a very powerful and flexible data structure. It can store multiple values, and these values ​​can be any type of data, including integers, strings, Boolean values, floating point numbers, etc. We can classify PHP arrays into several types based on the type of value stored.

1. Indexed array (Indexed Arrays): Indexed arrays are the most basic array type and use numeric indexing to access and manipulate values ​​in the array. The index starts from 0 and increases sequentially. For example, the following is an example of an indexed array:

$fruits=array("Apple","Banana","Orange");

In the above example, we created an indexed array named $fruits, which contains three fruit names. We can use indexes to access the value at a specific position, for example $fruits[0] will return "Apple" and $fruits[1] will return "Banana".

2. Associative array (Associative Arrays): Associative arrays are an array type that use string keys to access and manipulate values ​​in the array. Each value is associated with a unique key. The following is an example of an associative array:

$student=array("name"=>"John","age"=>20,"grade"=>"A");

In the above example, we created an associative array named $student, which contains three key-value pairs. We can use key names to access specific values, for example $student["name"] will return "John" and $student["age"] will return 20.

3. Multidimensional array (Multidimensional Arrays): Multidimensional arrays are a nested array type in which each element can itself be an array. By creating multi-dimensional arrays, we can create more complex data structures to store and process data. Here is an example of a multidimensional array:

$students=array(
array("name"=>"John","age"=>20,"grade"=>"A"),
array("name"=>"Emily","age"=>22,"grade"=>"B"),
array("name"=>"David","age"=>21,"grade"=>"C")
);

In the above example, we have created a multidimensional array called $students where each element is itself an associative array. We can use consecutive indexes and key names to access values ​​at specific positions. For example, $students[0]["name"] will return "John" and $students[1]["grade"] will return "B".

4. Constant array (Constant Arrays): A constant array is an array type that defines an array as a constant. By defining an array as a constant, you ensure that the array's value will not be modified throughout the script. The following is an example of a constant array:

define("FRUITS",array("Apple","Banana","Orange"));

In the above example, we created a constant array named FRUITS, which contains three fruit names. We can directly use constant names to access and operate on the values ​​of the array, such as echo FRUITS[0] will return "Apple".

To sum up, according to the type of stored value, PHP arrays can be divided into index arrays, associative arrays, multidimensional arrays and constant arrays. Each type has its own characteristics and applicable scenarios. Developers can choose the appropriate array type to store and process data according to specific needs. .

The above is the detailed content of PHP arrays are divided into several types of arrays by type. For more information, please follow other related articles on the PHP Chinese website!