Check number sequence

[mrmos]

Does anyone know if there is a php function to check if a set of numbers are in sequence? For example 1,2,3,4,5 or 23,24,25.

 

If there isn't a function to do this could anyone suggest the best way to do this?

 

Thanks 

[lemmin]

You could do this:

if(array_intersect($needle, $haystack) == $needle)
   echo "Sequence is in array";

 

That matches even if they are out of order, though. If you want to match the order too, you can just keep them as a string (or put them into a string) and simply match it with strstr or regex.

[ignace]

I think this should do the trick:

 

function checkSequence($array) {
    $lowest = min($array);
    $inSequence = true;
    $sizeof = sizeof($array);
    for ($i = 0; $i < $sizeof; ++$i) {
        if ($lowest !== $array[0]) {
            $inSequence = false;
            break;
        } else if (isset($array[$i + 1]) && $array[$i] > $array[$i + 1]) {
                $inSequence = false;
                break;
            }
        }
    }
    return $inSequence;
}

[lemmin]

Oh woops. My brain added an 'a' in between your "in" and "sequence." Now you know how to check if a set of numbers are in a sequence, though. 

[mrmos]

Nice function! Maybe there's a small bug in it as with the following two arrays it returns true?

 

$a1= array(1,2,3,4,5,6);
$a2= array(3,4,5,12,15);

 

 

[lemmin]

You could do it like this, too:

function checkSequence($array)
{
   $last = $array[0];
   for($i=1;$i<sizeof($array);$i++)
   {
      if ($array[$i] != $last+1)
         return false;
      $last = $array[$i];
   }
   return true;
}

[mrmos]

Great stuff lemmin, that works a treat!!

[ignace]

An even simpler solution would be:

 

if ($array == array_intersect(range(min($array), max($array)), $array))) {
    //in sequence
}

 

This will return true for:

 

$a1= array(1,2,3,4,5,6);

 

and returns false for:

 

$a2= array(3,4,5,12,15);