note 114078 added to language.types.array

There is another kind of array (php>= 5.3.0) produced by $array = new SplFixedArray(5); Standard arrays, as documented here, are marvellously flexible and, due to the underlying hashtable, extremely fast for certain kinds of lookup operation. Supposing a large string-keyed array $arr=['string1'=>$data1, 'string2'=>$data2 etc....] when getting the keyed data with $data=$arr['string1']; php does *not* have to search through the array comparing each key string to the given key ('string1') one by one, which could take a long time with a large array. Instead the hashtable means that php takes the given key string and computes from it the memory location of the keyed data, and then instantly retrieves the data. Marvellous! And so quick. And no need to know anything about hashtables as it's all hidden away. However, there is a lot of overhead in that. It uses lots of memory, as hashtables tend to (also nearly doubling on a 64bit server), and should be significantly slower for integer keyed arrays than old-fashioned (non-hashtable) integer-keyed arrays. For that see more on SplFixedArray : http://uk3.php.net/SplFixedArray Unlike a standard php (hashtabled) array, if you lookup by integer then the integer itself denotes the memory location of the data, no hashtable computation on the integer key needed. This is much quicker. It's also quicker to build the array compared to the complex operations needed for hashtables. And it uses a lot less memory as there is no hashtable data structure. This is really an optimisation decision, but in some cases of large integer keyed arrays it may significantly reduce server memory and increase performance (including the avoiding of expensive memory deallocation of hashtable arrays at the exiting of the script). ---- Server IP: 72.52.91.14 Probable Submitter: 72.52.91.14 ---- Manual Page -- http://php.net/manual/en/language.types.array.php Edit -- https://master.php.net/note/edit/114078 Del: integrated -- https://master.php.net/note/delete/114078/integrated Del: useless -- https://master.php.net/note/delete/114078/useless Del: bad code -- https://master.php.net/note/delete/114078/bad+code Del: spam -- https://master.php.net/note/delete/114078/spam Del: non-english -- https://master.php.net/note/delete/114078/non-english Del: in docs -- https://master.php.net/note/delete/114078/in+docs Del: other reasons-- https://master.php.net/note/delete/114078 Reject -- https://master.php.net/note/reject/114078 Search -- https://master.php.net/manage/user-notes.php