Question

I made a textbox labeled as “Page Numbers“.

The user may enter the page numbers in any sequence like 1, 3, 6.

I want to handle that if user entered 1, 4, 2, 6-8, 10. Then I should know that the user selected page number 1, 2, 4, 6, 7, 8, 10.

That means the user can also enter the range as well as comma separated numbers like we give the page numbers while printing documents.

The order number of pages can also be changed. For e.g. 5, 6, 4-8, 1. The numbers can be repeated but I need only the unique page numbers.

How I can do it in PHP? Thanks in Advance.

Answer 1

Here’s the plan of attack:

1. Split the string by comma and iterate through the values
2. For each value validate that it’s either a number or two numbers separated by a hyphen
3. If it’s a single number, add it to your page number set
4. If it’s a range then split the string by hyphen
5. Determine which number is the smaller one and for loop from the smaller one to the larger one, each time adding the number to the set
6. Sort the set.

I’d make the set an assoc array and when I add a number to it I’d set it as the key. E.g.

$pageNumbers[$number] = true;

Here’s the code:

$pageNumberStr = $_REQUEST['pageNumberStr'];

$components = explode(",", $pageNumberStr);

$pageNumbers = array();

foreach ($components as $component) {
   $component = trim($component);
   if (preg_match('/^\d+$/', $component)) {
      $pageNumbers[$component] = true;
   } else if (preg_match('/^(\d+)-(\d+)$/', $component, $matches)) {
      $first = min($matches[1], $matches[2]);
      $last = max($matches[1], $matches[2]);

      for ($i = $first; $i <= $last; $i++) {
         $pageNumbers[$i] = true;
      }
   }
}

$pageNumbers = array_keys($pageNumbers);
sort($pageNumbers);