Find an array item from within another array?

[we5inelgr]

Hi all,

I've got an array that's built from a query.

$qArray = ("Blue", "Red", "Green", "White", "Black", "Yellow", "Purple")

I've also got an array that's built from user (form) input.

$uArray = ("2", "5", "6")

I'm trying to match up the array (index) number from the User input, to the color in $qArray.

What I've got now isn't working:

$cntr = 0;
foreach ($uArray as $key=>$value) {
    if ($key == $cntr) {
        echo $qArray[$cntr]."<br>";
    }
    $cntr++;
}

Nothing echo's out.

[Weedpacket]

I think you'll want to compare [font=monospace]$cntr[/font] with [font=monospace]$value[/font], not [font=monospace]$key[/font].

On the other hand [font=monospace]$cntr[/font] is kind of redundant anyway, since the only values of it that matter are those that are also values in [font=monospace]$uArray[/font], and you already have those:

foreach($uArray as $value)
{
    if(isset($qArray[$value]))
    {
        echo $qArray[$value] . "<br>";
    }
}

Things would go more cleanly if the submitted values are first converted to integers, rather than leave them as strings:

$uArray = array_map('intval', $uArray);

And if you can ensure that [font=monospace]$uArray[/font] only contains appropriate values by the time this code is reached then the [font=monospace]if[/font] test wouldn't be needed either.

[bradgrafelman]

You could also use [man]array_intersect_key/man and [man]array_flip/man:

$qArray = ["Blue", "Red", "Green", "White", "Black", "Yellow", "Purple"];
$uArray = ["2", "5", "6"];

$newArray = array_intersect_key($qArray, array_flip($uArray));

where newArray would then be:

Array
(
    [2] => Green
    [5] => Yellow
    [6] => Purple
)

[we5inelgr]

Thanks for the suggestion! Works great.