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What is the Big-O time complexity of the count() function for arrays?
Example
$x = array(1,2,3);
echo count($x); // how many operation does it takes to count the elements
// of the array? is it 3, or is it 1
255
The count() function returns the number of elements in an array.
How to Count all Elements or Values in an Array in PHP. We can use the PHP count() or sizeof() function to get the particular number of elements or values in an array. The count() and sizeof() function returns 0 for a variable that we can initialize with an empty array.
The array_count_values() function counts all the values of an array.
$ time php -r '$a=range(1,1000000); $b=0; for($i=0;$i<10;$i++) $b=count($a);'
real 0m0.458s
$ time php -r '$a=range(1,1000000); $a=array(1); $b=0; for($i=0;$i<10;$i++) $b=count($a);'
real 0m0.457s
Tested PHP version: PHP 5.3.3-1ubuntu9.1 with Suhosin-Patch (cli) (built: Oct 15 2010 14:00:18)
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