Count $_POST reply starting by "custom_"

Question

On my website, we can create a product with an unknown number of custom field. To insert my data inside the database, I want to know the number of inputs starting with "parameter" (in my data below).

How can I count() the POST result starting with "parameter"? Thanks

array(6) {
    ["quantity"]=> string(8) "200"
    ["price"]=> string(4) "150"
    ["product_supplier"]=> string(4) "1"
    ["parameter1"]=> string(4) "text"
    ["parameter2"]=> string(7) "Exemple"
    ["parameter3"]=> string(4) "text"
}

Answer 1

Use array_keys to get the keys of the array, and then iterate through using a foreach or array_reduce eg

$count = 0;
foreach (array_keys($array) as $key) {
    if (strpos($key, 'parameter') === 0) $count++;
}
echo "$count parameters\n";

$count = array_reduce(array_keys($array), function ($c, $v) { 
    if (strpos($v, 'parameter') === 0) $c++; 
    return $c; },
    0);
echo "$count parameters\n";

Output (for your sample data):

3 parameters

Demo on 3v4l.org

You might instead want to consider naming your parameter inputs using PHP's array notation eg

<input type="text" name="parameters[]" />

Then all your parameter inputs will appear as an array in $_POST['parameters'] and you can get the count easily via

echo count($_POST['parameters']);

It will probably make it easier to process the parameters too as you can use a simple foreach :

foreach ($_POST['parameters'] as $parameter) {
    // do stuff
}