In php, the number of m is n. What should I do if it exceeds the memory?

Below is the code I found online: {code ...} {code ...} output result: Array ({code ...}) my $ arr has hundreds of elements and exceeds the memory after execution. What should I do? Can someone help improve the combined functions? I am weak in this regard. I don't know how to do this? The code I found online is as follows:

function getCombinationToString($arr,$m){    $result = array();    if ($m ==1)    {        return $arr;    }    if ($m == count($arr))    {        $result[] = implode(',' , $arr);        return $result;    }    $temp_firstelement = $arr[0];    unset($arr[0]);    $arr = array_values($arr);    $temp_list1 = getCombinationToString($arr, ($m-1));    foreach ($temp_list1 as $s)    {        $s = $temp_firstelement.','.$s;        $result[] = $s;    }    unset($temp_list1);    $temp_list2 = getCombinationToString($arr, $m);    foreach ($temp_list2 as $s)    {        $result[] = $s;    }    unset($temp_list2);    return $result;}

$arr=['a','b','c','d','e','f'];getCombinationToString($arr,3);

Output result:

Array
(

[0] => a,b,c[1] => a,b,d[2] => a,b,e[3] => a,b,f[4] => a,c,d[5] => a,c,e[6] => a,c,f[7] => a,d,e[8] => a,d,f[9] => a,e,f[10] => b,c,d[11] => b,c,e[12] => b,c,f[13] => b,d,e[14] => b,d,f[15] => b,e,f[16] => c,d,e[17] => c,d,f[18] => c,e,f[19] => d,e,f

)
My $ arr has hundreds of elements and exceeds the memory after execution. What should I do? Can someone help improve the combined functions? I am weak in this regard. I don't know how to do this?

Reply content:

The code I found online is as follows:

function getCombinationToString($arr,$m){    $result = array();    if ($m ==1)    {        return $arr;    }    if ($m == count($arr))    {        $result[] = implode(',' , $arr);        return $result;    }    $temp_firstelement = $arr[0];    unset($arr[0]);    $arr = array_values($arr);    $temp_list1 = getCombinationToString($arr, ($m-1));    foreach ($temp_list1 as $s)    {        $s = $temp_firstelement.','.$s;        $result[] = $s;    }    unset($temp_list1);    $temp_list2 = getCombinationToString($arr, $m);    foreach ($temp_list2 as $s)    {        $result[] = $s;    }    unset($temp_list2);    return $result;}

$arr=['a','b','c','d','e','f'];getCombinationToString($arr,3);

Output result:

Array
(

[0] => a,b,c[1] => a,b,d[2] => a,b,e[3] => a,b,f[4] => a,c,d[5] => a,c,e[6] => a,c,f[7] => a,d,e[8] => a,d,f[9] => a,e,f[10] => b,c,d[11] => b,c,e[12] => b,c,f[13] => b,d,e[14] => b,d,f[15] => b,e,f[16] => c,d,e[17] => c,d,f[18] => c,e,f[19] => d,e,f

)
My $ arr has hundreds of elements and exceeds the memory after execution. What should I do? Can someone help improve the combined functions? I am weak in this regard. I don't know how to do this?

You can generate an output.