How to define php global array

In PHP, the global array is a very useful data structure that can be used throughout the script, including functions and various methods of classes. In this article, we will explore how global arrays are defined, and also introduce some basic concepts and operations about global arrays.

Global array refers to an array that can be accessed throughout the execution of the script. This kind of array can be defined outside the function body or in a class, and can be used in multiple functions and methods. Global arrays are very common in PHP and can be used to store some important data, such as website configuration information, user login status, etc.

In PHP, there are usually two ways to define a global array: using the $GLOBALS array and using the keyword global. Below we will introduce these two methods respectively.

Using the $GLOBALS array

$GLOBALS is a super global variable in PHP that can be accessed throughout the script. It is an associative array that stores all global variables, including global arrays. Global arrays can be defined and accessed through the $GLOBALS array.

The following is an example of using $GLOBALS to define a global array:

// 定义一个全局数组
$GLOBALS['config'] = array(
    'db_host' => 'localhost',
    'db_username' => 'root',
    'db_password' => 'password123',
    'db_name' => 'my_database'
);

// 访问全局数组
echo $GLOBALS['config']['db_host'];

In the above example, we use $GLOBALS to define a global array named $config and give It assigns an array containing database connection information. Subsequently, we use the $GLOBALS array to access the elements in the global array and output the database host address.

Of course, we can also access the $GLOBALS array anywhere in the script without worrying about scope or function and method restrictions.

Using the global keyword

In addition to using the $GLOBALS array, we can also use the global keyword in PHP to define and access global arrays. When using the global keyword, you need to first introduce the global array into the function or method.

The following is an example of using global to define a global array:

// 定义一个全局数组
$config = array(
    'db_host' => 'localhost',
    'db_username' => 'root',
    'db_password' => 'password123',
    'db_name' => 'my_database'
);

// 函数内部引入全局数组
function connect_to_database() {
    global $config;
    $mysqli = new mysqli($config['db_host'], $config['db_username'], $config['db_password'], $config['db_name']);
    return $mysqli;
}

// 在外部访问全局数组
echo $config['db_host'];

In the above example, we use the global keyword to introduce the global array into the function connect_to_database() and access it through The elements in this array implement the connection to the database. At this point, we can access the global array inside the function or method, and we can also access the array outside the function or method.

In addition, we can also use some other useful features of PHP to operate global arrays, including the unset() function, variable reference character "&", etc. These features allow us to operate global arrays more conveniently.

Summary

In PHP, the global array is a very useful data structure that can be used throughout the script, including functions and various methods of classes. Using the $GLOBALS array and the global keyword are two common ways to define and access global arrays. Developers can also use other features of PHP to operate global arrays. Proficient in these methods and features will allow us to use global arrays in PHP more conveniently and efficiently.

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