Count Similar Array Keys

Question

I have a POST request coming to one of my pages, here is a small segment:

[shipCountry] => United States
[status] => Accepted
[sku1] => test
[product1] => Test Product
[quantity1] => 1
[price1] => 0.00

This request can be any size, and each products name and quantity's key would come across as "productN" and "quantityN", where N is an integer, starting from 1.

I would like to be able to count how many unique keys match the format above, which would give me a count of how many products were ordered (a number which is not explicitly given in the request).

What's the best way to do this in PHP?

Answer 1

Well, if you know that every product will have a corresponding array key matching "productN", you could do this:

$productKeyCount = count(preg_grep("/^product(\d)+$/",array_keys($_POST)));

preg_grep() works well on arrays for that kind of thing.

Answer 2

What Gumbo meant with his "use array instead" comment is the following:

In your HTML-form use this:

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

and $_POST['quantity'] will then be an array of all containing all of your quantities.

If you need to supply an id you can also do this:

<input type="text" name="quantity[0]" />

$_POST['quantity][0] will then hold the corresponding quantity.

Answer 3

As mentioned by gumbo you could group all parameters describing one item in its own array which usually makes it easier to iterate them. You may not have control over the POST parameters but you can restructure them like e.g. with

<?php

$testdata = array(
  'shipCountry' => 'United States',
  'status' => 'Accepted',
  'sku1' => 'test1',
  'product1' => 'Test Product1',
  'quantity1' => '1',
  'price1' => '0.01',
  'sku2' => 'test2',
  'product2' => 'Test Product2',
  'quantity2' => '2',
  'price2' => '0.02'
);

$pattern = '/^(.*\D)(\d+)$/';
$foo = array('items'=>array());
foreach($testdata as $k=>$v) {
  if ( preg_match($pattern, $k, $m) ) {
    $foo['items'][$m[2]][$m[1]] = $v;
  }
  else {
    $foo[$k] = $v;
  }
}
print_r($foo);

Answer 4

Though there be plenty of examples, if you're guaranteed that the numbers should be contiguous, I usually take the approach:

<?php 
$i = 1; 
while( isset($_POST['product'.$i) )
{
    // do something
    $i++;
}