Just wondering about the performance impact of copying very large php variables. For example say $arr is an enormous array. If I do $arr2 = $arr, is this a deep copy or is $arr2 merely a pointer to $arr like it is in Java? Thanks in advance.
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1*(reference)* Copy on Write in the PHP language: http://www.research.ibm.com/trl/people/mich/pub/200901_popl2009phpsem.pdf – Gordon Mar 05 '10 at 08:10
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$arr2 = $arr creates a deep copy. But the actual copying only happens when $arr2 is modified -- PHP utilizes copy-on-write.
If you want a "pointer" instead of a copy, use $arr2 =& $arr, which makes $arr2 a reference to $arr.
Frank Farmer
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The general rule in PHP is don't create references unless you need the functionality they provide. References will only make the code slower otherwise.
Matthew
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