phpied.com

When copying one resource to another, you're actually creating a reference to the original resource, this is not an actual copy.

This is illustrated by the following example:

echo '<pre>';
// create an image resource
$image = imagecreate(100, 100);


// print the resource
var_dump($image);
// the above prints "resource(30) of type (gd)"

// create a copy 
// (actually creating a reference, 
// although =& is not implicitly used)
$copy = $image;

// print the reference
var_dump($copy);

// the above prints "resource(30) of type (gd)", same as before

// destroy the image resource
imagedestroy($image);

// this prints "resource(30) of type (Unknown)"
// so the image was destroyed
var_dump($image);

// this also prints "resource(30) of type (Unknown)"
// meaning that the reference points to a destroyed image
var_dump($copy);


echo '</pre>';

This entry was posted on Wednesday, September 7th, 2005 and is filed under PHP certification. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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