Question

I need to set an array from 1 to 2 million for my current project. The problem is that I get a memory error when I try to execute…

Edit:

This is for a ProjectEuler problem which I have already solved. However, I am refactoring the code to do it much faster (original time was ~90 secs).

I’m using the sieve of eratosthenes to mark the primes from 0 to 2mil. Wikipedia article on this

EndEdit

<?php
range(0,2000000);
?>

obviously if this won’t work, the rest of the code won’t work.

Any ideas?

P.S. I tried ini_set('memory', '30M'); , but that didn’t work either.

Edit

Thanks to all who pointed out that the memory would need to be much larger than I first anticipated. I solved the problem by throwing in ini_set('memory_limit', '4000000000'); //about 3.73 gig

EndFinalEdit

Answer 1

If you can set at arbitrary place and get data from arbitrary index there is no point of sequential array.

// completely acceptable in php
$data[2000000] = 2000000; 

If you are solving this euler problem in console (what I usually do), then run the php file with -d memory_limit=4G parameter. It’ll run with 4 GB of memory.

php -d memory_limit=4G /path/to/euler/problem.php 

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BTW You can create some magic class which can mimic that you have a big array like that. 🙂

class MySuperCoolLongIntArray{
    private $data=array();
    public get_int($index){
        return isset($this->data[$index])? $this->data[$index]: 0;
    }
    public set_int($index, $value){
        $this->data[$index]=$value;
    }
}