Question

I’m not sure about an error I’m getting while accessing a two-dimensional array in PHP.
Basically my var_dump() gives me the following:

 array(1) {
   ['x']=>
     string(1) "3"
 }
 array(1) {
   ['y']=>
     string(3) "3"
 }

 array(1) {
   ['x']=>
     string(1) "5"
 }
 array(1) {
   ['y']=>
     string(3) "5"
 }

The var_dump is imho correct and shows the results I wanted to achieve.

What I’m doing is the following:
1) preparing x and y coordinates within an $points array
2) check if some numbers are within the coordinates given:

    function check_collisions {
    $points = array();
    for($y = 0; $y < count($this->Ks); $y++)
    {
        $points[]['x'] = $this->Ks[$y][0]; // first is 3, second is 5 - see var_dump above
        $points[]['y'] = $this->Ks[$y][1]; // first is 3, second is 5 - see var_dump above
    }


    for($p = 0; $p < count($points); $p++)
    {
        for($r = 0; $r < count($this->Ns); $r++)
        {
            if($points[$p]['x'] >= $this->Ns[$r][0] && $points[$p]['x'] <= $this->Ns[$r][2])
            {

                if($points[$p]['y'] >= $this->Ns[$r][1] && $points[$p]['y'] <= $this->Ns[$r][3])
                {

                    $collisions++;
                }
            }
        }
    }
    return $collisions;
    }

My PHP now tells me that x and y are undefined indexes within the two if conditions. Is there anything wrong? The other indexes are working well, like accessing $this->Ns etc.
Any ideas?

Answer 1

Change your for loop to look like this:

for($y = 0; $y < count($this->Ks); $y++)
{
    $points[] = array('x' => $this->Ks[$y][0], 'y' => $this->Ks[$y][1]);
}

When you assign to $points[] with no index it appends to the array every time. You are appending two arrays to $points each loop instead of a single array with the coordinates.