How to access global variables inside a function in PHP

In PHP, global variables are variables accessible in functions, classes, and scripts. These variables can be declared and initialized by specifying the $GLOBALS array, or they can be declared as global variables inside the function. However, it is not easy to access global variables in a function, because the function is a local scope structure, so how to access global variables inside the function?

One way is to use the $GLOBALS array. For example:

<?php
$number = 50;

function change_number() {
    global $number;
    $number = 100;
}

change_number();
echo $number; // 输出: 100
?>

In the above example, we have used the global keyword to declare $number as a global variable, so inside the function $number After the value of is modified, it also changes outside the function.

Another approach is to use $GLOBALSsuper global arrays. For example:

<?php
$number = 50;

function change_number() {
    $GLOBALS[&#39;number&#39;] = 100;
}

change_number();
echo $number; // 输出: 100
?>

In the above example, the $number key value in $GLOBALS corresponds to the global variable $number. When we modify the value of $GLOBALS['number'] inside the function, the value of the global variable $number is also modified.

It should be noted that excessive use of global variables may make the code difficult to maintain. If you need to use a lot of variables inside a function, it's better to pass them into the function from outside to avoid dependencies between functions.

To sum up, you can access and modify global variables using the global keyword or the $GLOBALS array. However, you need to use global variables with caution and use variables as function parameters whenever possible to avoid code that is cluttered and difficult to maintain.

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