CODEWITHSUNDEEP
phpfunctionscope
AmbroseChapel
AmbroseChapel

Reputation: 12097

PHP and function scope

I was wondering what exactly happens when I do this:

$my_variable = 'foo';
function whatever(){
    $my_variable = 'bar';
    global $my_variable;
}

I know that, within the scope of the function $my_variable is now 'foo'.

What's going on internally? When I do $my_variable = 'bar'; inside my function, I've created a local variable. When I do global $my_variable; on the next line what exactly happens? The local one is automatically deleted?

Upvotes: 3

Views: 132

Answers (3)

periklis
periklis

Reputation: 10188

Think of it like this:

$GLOBALS['my_variable'] = 'foo';
function whatever(){
    $my_variable = 'bar';
    $my_variable = $GLOBALS['my_variable'];
}

Upvotes: 0

hakre
hakre

Reputation: 198247

Yes, the local one is automatically deleted or probably better worded, it is replaced with the global variable.

Upvotes: 2

Marc B
Marc B

Reputation: 360872

Up until the global is processed, the function will be using the local bar copy of the varaible. Once it's declared global, the local version is hidden (or maybe destroyed, not sure...) and only the global version is available. e.g:

$z = 'foo';
function whatever() {
    echo $z; // warning: undefined variable
    $z = 'bar';
    echo $z; // bar
    global $z;
    echo $z; // foo
}
whatever();

Upvotes: 2

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