PHP in_array不会检查所有情况

Question

I'm removing values from an array in PHP use an in_array check yet for some reason it does not want to check through the entire length of the exclude array . Running this code it removes the Dodge entries from the array but not the Toyota, why is this?

<?php

    $inventory = array(
        '0' => Array
            (
                'car_name' => 'Dodge',
                'set_name' => 'A',
                'edition' => 'B41',
                'location' => 'Houston'
            ),

        '1' => Array
            (
                'car_name' => 'Dodge',
                'set_name' => 'A',
                'edition' => 'B41',
                'location' => 'Houston'
            ),

        '2' => Array
            (
                'car_name' => 'Dodge',
                'set_name' => 'A',
                'edition' => 'B41',
                'location' => 'Houston'
            ),

        '3' => Array
            (
                'car_name' => 'Dodge',
                'set_name' => 'A',
                'edition' => 'VarA31',
                'location' => 'Houston'
            ),

        '4' => Array
            (
                'car_name' => 'Toyota',
                'set_name' => 'A',
                'edition' => 'VarA31',
                'location' => 'Houston'
            ),

        '5' => Array
            (
                'car_name' => 'Toyota',
                'set_name' => 'A',
                'edition' => 'VarA31',
                'location' => 'Houston'
            ),

        '6' => Array
            (
                'car_name' => 'Toyota',
                'set_name' => 'A',
                'edition' => 'VarA31',
                'location' => 'Houston'
            ),

        '7' => Array
            (
                'car_name' => 'Toyota',
                'set_name' => 'A',
                'edition' => 'VarA31',
                'location' => 'Houston'
            ),

        '8' => Array
            (
                'car_name' => 'Toyota',
                'set_name' => 'A',
                'edition' => 'VarA31',
                'location' => 'Houston'
            ),

        '9' => Array
            (
                'car_name' => 'Toyota',
                'set_name' => 'A',
                'edition' => 'VarA31',
                'location' => 'Houston'
            ),

        '10' => Array
            (
                'car_name' => 'Toyota',
                'set_name' => 'A',
                'edition' => 'VarA31',
                'location' => 'Houston'
            ),

        '11' => Array
            (
                'car_name' => 'Toyota',
                'set_name' => 'A',
                'edition' => 'VarA31',
                'location' => 'Houston'

            ),
    );

    $exclude = array('Dodge','Toyota');

    for($k=0; $k<sizeof($inventory); $k++)
    {
    if(in_array(trim($inventory[$k]['car_name']), $exclude))
    {   unset($inventory[$k]);}

    }

         $inventory = array_values($inventory);
         echo '<pre>';
         print_r($inventory);
         echo '</pre>';



    ?>

Answer 1

Your problem is that unsetting an element from an enumerated array will adjust the size of your array, but testing using sizeof() to see if you should exit your loop, so each iteration where you unset will reduce the number of values left to test.

$exclude = array('Dodge','Toyota');

$size = sizeof($inventory);
for($k=0; $size; $k++) {
    if(in_array(trim($inventory[$k]['car_name']), $exclude)) {
        unset($inventory[$k]);
    }
}

$inventory = array_values($inventory);
echo '<pre>';
print_r($inventory);
echo '</pre>';

Answer 2

You are removing the index:value pair from the array, while iterating it. So after unsetting a value the index positions dont match or even exist.

Try copying the values you do need, into a new empty array like this:

$exclude = array('Dodge','Toyota');
$filtered = array();

for($k=0; $k<sizeof($inventory); $k++){
    if(in_array(trim($inventory[$k]['car_name']), $exclude)){
        // dont do this because it is changing the count of elements in the array unset($inventory[$k]);
    } else {
        $filtered[] = $inventory[$k]; // push the desired values into a new array
    }
}

echo '<pre>';
print_r($filtered);  // this should have the values that don't have 'Dodge' or 'Toyota'
echo '</pre>';

Edit: Mark's answer would be the best way to go cause it is also better performance wise

Answer 3

use foreach instead for($k=0; $k<sizeof($inventory); $k++) :

foreach($inventory as $k => $row)

this is because while you are unsetting $inventory you skip elements

$k = 0, sizeof($inventory) = 12, you unset one of the items, $k++ . $inventory[1] becomes $inventory[0]

$k = 1, sizeof($inventory) is now 11, you check $inventory[1] but not $inventory[0] (previous known as $inventory[1] )