Question

I have to pass an index to a function and from that index return a string containing from 1 to 4 chars.

I have:

$string = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';

So if I say index(20) the function should return lower “k” because it is its index in the $string variable.

But…

If I type indexes

62 it should return 10
63 .. 11

That is because from index 62 it should start the string from 1, not 0, and loop until the next index, so they will be 2 length string

If I type indexes

3843 .. ZZ

That is because from index 3843 all the possibilities from [0-9a-zA-Z][0-9a-zA-Z] have ended and now the string starts with 3 length.

3844 .. 100

...

9999 .. 2Bh

All the possibilities and at [0-9a-zA-Z][0-9a-zA-Z][0-9a-zA-Z] but I only need until index 9999

Answer 1

Your question is a bit hard to understand, not sure if this is what you want:

$string = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'; 

function t($n)
{
    global $string;
    $ret = $string{$n%62};
    if($n>=62)
        $ret = t(floor($n/62)).$ret;
    return $ret;
}

echo t(9999);