PHP removes null-valued elements from arrays (array

Ashamed to say, before the null values of the array are all strong write foreach or while, using these two syntactic structures to delete the empty elements in the array, simple code is as follows:

<?php   
foreach ($arr as $k => $v) {
    if (! $v) unset ($arr [$k]);   
}

It turns out that if the array is too large, the efficiency of this process is not high. Because foreach is the current operation of the array copy, each operation of foreach, is a copy of a variable, the page if there are too many foreach, will be a great consumption.

Wandering on the Internet, see people have hints with array_filter, so open the manual looked, found himself has been guarding a baoshan but do not know how to use.

The function of the Array_filter function is to use the callback function to filter the array, and if there is no callback function, the default is to delete the item whose value is False. The following example:

<?php
$entry = Array (   
	0 => ' foo ',   
	1 => false,   
	2 =>-1,   
	3 => NULL,   
	4 => '
);
Print_r (Array_filter ($entry));

The output value is:

Array
(
[0] => foo
[2] =>-1
)

Recommendation: PHP is the most important two chapters should be array operation and string operation, the two chapters inside the function must be skilled, the other is used when the time to check it.

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