Find the first missing number in a sequence of numbers

Question

It\'s the second day I try to find a solution for this problem.

I have an array.

$datas;

$datas[0]; // 8000
$datas[1]; // 8001
$datas[2]; // 8003
$datas         


        

Answer 1

Sort from lowest to highest (if not already sorted) and then increment from the lowest and check if it is in the array:

sort($datas); 
for($i=reset($datas); in_array($i, $datas); $i++);
echo $i;

reset gets the first number, in this case 8000 to start and the in_array condition terminates the loop when $i is not in the array.