php multidimensional SplFixedArray declaration is throwing fatal error

Question

I want to declare SplFixedArray(); to save memory consumption. but it is throwing fatal error.

$items=new SplFixedArray();
echo "Array Started...";
    for($h=0;$h<5000;$h++)
    {   
        for($i=0;$i<24;$i++)
        {   
            $items[$h][$i]=$objSheet->getCellByColumnAndRow($i,$h+1)->getValue();
        }
    }

The same is working if do not declare new SplFixedArray();

Error:

Fatal error: Uncaught exception 'RuntimeException' with message 'Index invalid or out of range' in /home/twa/files.php:168 Stack trace: #0 /home/twa/files.php(168): unknown() #1 {main} thrown in /home/twa/files.php on line 168

$items=new SplFixedArray(SplFixedArray()); is also failing...

Please let me know correct syntax...

Answer 1

$items = new SplFixedArray(5000);
for ($h=0; $h<5000; $h++) {
    $items[$h] = new SplFixedArray(24);
    for ($i=0; $i<24; $i++) {
        $items[$h][$i] = $objSheet->getCellByColumnAndRow($i,$h+1)->getValue();
    }
}