$GLOBALS

$GLOBALS is an array of every variable in the global scope. Because it is a superglobal, you can use it inside functions without global.

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<?php
$siteName = "Code Corner";

function showSite(): void
{
    echo $GLOBALS["siteName"];
}

showSite();

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Code Corner

Writing a global variable

You can create or change a single global through its key.

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<?php
$counter = 0;

function increase(): void
{
    $GLOBALS["counter"]++;
}

increase();
increase();

echo $counter;

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PHP 8.1 restrictions

In PHP 8.1, $GLOBALS became a read-only copy of the global symbol table, with one exception: writing to a single key ($GLOBALS["x"] = 1) is still allowed. These no longer work:

• $GLOBALS = [];
• foreach ($GLOBALS as &$value) (by reference)
• array_pop($GLOBALS) and other functions that take the whole array by reference

If you maintain old code that does that, it needs a change.

$GLOBALS vs the global keyword

Both do the same job. Neither is a good habit.

The problem with globals

• A function hides its inputs. You cannot tell what it needs by reading its signature.
• Any code anywhere can change the value.
• Testing is harder.

Pass what the function needs as parameters instead:

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<?php
function showSite(string $siteName): void
{
    echo $siteName;
}

showSite("Code Corner");

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Code Corner