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phpsplarray-map

array_map vs loop and operation

Using:

for($i=1; $i<= 10000; ++$i) {
    $arrayOfNumbers[] = rand(1, 99999);
}

Can some explain why there is such a speed difference:

array_map(array($maxHeap, 'insert'), $arrayOfNumbers);
# Avg Time: 0.92856907844543s

# against

foreach($arrayOfNumbers as $number) {
    $maxHeap->insert($number);
}
# Avg Time: 1.3148670101166

$maxHeap being an object class MaxHeap extends SplMaxHeap

Solution

  • It is due to the difference between Callback functions and normal functions.

    In the second one, iteration of array using foreach, each iteration calls "insert" function and wait for the execution (function return control) and proceed to next iteration.

    But in the array_map function, "insert" happens as callback function, it calls "insert" and don't wait for the result and call insert with next item in the array. So it is faster.

    Hope it helps.