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I have an array thats got about 12 potential key/value pairs. That are based off a _POST/_GET

The keys are not numeric as in 0-n, and I need to retain the keys with there values where applicable. My issue is I know that on occasion a key will be passed where the value is null, empty, or equal to ''. In the event thats the case I want to trim out those keys before processing my array. As running down the line without something there is going to break my script.

Now a while back I either made or found this function (I don't remember which its been in my arsenal for a while, either way though).

function remove_array_empty_values($array, $remove_null_number = true)
    {
        $new_array = array();
        $null_exceptions = array();
        foreach($array as $key => $value)
        {
            $value = trim($value);
            if($remove_null_number)
            {
                $null_exceptions[] = '0';
            }
            if(!in_array($value, $null_exceptions) && $value != "")
            {
                $new_array[] = $value;
            }
        }
        return $new_array;
    }

What I would love to do is very similar to this, however this works well with arrays that can have n-n key values and I am not dependent upon the key as well as the value to determine whats what where and when. As the above will just remove everything basically then just rebuilt the array. Where I am stuck is trying to figure out how to mimic the above function but where I retain the keys I need.

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1  
Unless I misunderstand the requirement, that is the exact function of array_filter() – Michael Berkowski Mar 5 '12 at 14:14
possible duplicate of Remove zero values from a PHP array – hakre Mar 5 '12 at 14:38
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2 Answers

up vote 2 down vote accepted

If I understand correctly what you're after, you can use array_filter() or you can do something like this:

foreach($myarray as $key=>$value)
{
    if(is_null($value) || $value == '')
        unset($myarray[$key]);
}
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You may wish to use if ( empty( $value ) ) to be more comprehensive. – George Cummins Mar 5 '12 at 14:20
@GeorgeCummins: agree, that's an option. Internally, it does the same thing though - right? – Aleks G Mar 5 '12 at 14:21
empty() is more comprehensive because it also checks for 0, false, "0", 0.0, empty arrays, etc. It is also a little simpler to read and maintain. – George Cummins Mar 5 '12 at 14:23
@GeorgeCummins Fair enough, however this is not what he wants: he states that he only wants to filter out nulls and empty strings. – Aleks G Mar 5 '12 at 14:32
@chris said: "where the value is null, empty, or equal to '' ." Since he specifically said "empty" and didn't say "empty string" I assumed my interpretation was correct. Perhaps a little clarification from from the asker would be helpful. – George Cummins Mar 5 '12 at 14:40
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up vote 2 down vote

array_filter is a built-in function that does exactly what you need. At the most you will need to provide your own callback that decides which values stay and which get removed. The keys will be preserved automatically, as the function description states.

For example:

// This callback retains values equal to integer 0 or the string "0".
// If you also wanted to remove those, you would not even need a callback
// because that is the default behavior.
function filter_callback($val) {
    $val = trim($val);
    return $val != '';
}

$filtered = array_filter($original, 'filter_callback');
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