如何通过PHP substr（）函数覆盖/更改前导零的默认删除？ [关闭]

In PHP when we do a substr() such that the resultant string should be something like 0004, PHP automatically removes the leading 0s and just gives 4.

I want to avoid this behavior. I want the leading zeroes to stay there. How can I enforce that?

Forexample the following snippet prints 4.

echo substr("100041", 1, 4);

How can I force it to print 0004?

Who said? Php doesn't remove 0 in string...

enter image description here

Anyway create a own function..

<?php

function substring($data,$from,$length){

    $sub = "";
    $data = str_split($data);
    $i = 0;
    $l = 1;
    foreach($data as $letter){

        if($i >= $from && $l <= $length){

            $sub .= $letter;
            $l = $l+1;
        }

        $i = $i+1;
    }

    return $sub;
} 

echo substring("100041", 1, 4);

?>

It doesn't:

var_dump(substr("100041", 1, 4));

string(4) "0004"

(online demo)

As per documentation this is a 100% string function. It doesn't handle numbers in any special way.