How to declare an array in php (three ways)

In PHP, there are many ways to declare arrays. This article will detail the different ways of declaring arrays in PHP.

1. Use the array() function to declare an array

In PHP, we can use the array() function to declare an array. The format is as follows:

array(value1, value2, ..., valueN)

Among them, value1 , value2,..., valueN are all elements of the array. As in the following example, an array containing three elements is declared:

$cars = array("Volvo", "BMW", "Toyota");

In the above example, $cars is an array variable, which contains three string elements: "Volvo", "BMW" and "Toyota".

2. Use square brackets to declare an array

We can also use square brackets [] to declare an array, the format is as follows:

array[index1] = value1;
array[index2] = value2;
......
array[indexN] = valueN;

In the above code, array is Array name, index1, index2,..., indexN are the keys (subscripts) corresponding to each element in the array, value1, value2,..., valueN are the values ​​corresponding to the keys.

As the following code example:

$cars[0] = "Volvo";
$cars[1] = "BMW";
$cars[2] = "Toyota";

In the above example, $cars is an array variable, which contains three string elements: "Volvo", "BMW" and "Toyota" . Their subscripts are 0, 1 and 2 respectively.

3. Use short syntax to declare an array

Since PHP version 5.4, we can also use short syntax to declare an array. It allows for a more concise declaration of an array, and can also contain keys and values. The format is as follows:

array = [key => value, key2 => value2, ..., keyN => valueN];

The following code example:

$cars = ["Volvo" => "XC90", "BMW" => "X5", "Toyota" => "Highlander"];

In the example, $cars is an array containing three key-value pairs. Among them, the keys are "Volvo", "BMW", and "Toyota", and the corresponding values ​​are "XC90", "X5", and "Highlander" respectively.

It should be noted that arrays in PHP are dynamic arrays, that is, elements can be added, modified, and deleted at any time after they are declared. Also, in PHP, array elements can be accessed by their keys or values.

To sum up, this article introduces three ways to declare arrays in PHP, namely using the array() function, using square brackets to declare and using short syntax to declare. For different needs, you can choose the appropriate method.

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