loop through multiple arrays incrementing length of string

Question

I have

$char=array("1","2","3","4","5","6","7","8","9","0","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","-");
$doma=array("aero","asia","biz","cat","com","coop","info","int","jobs","mobi","museum","name","net","org","pro","tel","travel","xxx","edu","gov","mil","co.uk","co.nr","co.au","au","ca","co.cc","cc","co","cn","co.jp","de","es","ie","in","it","jp","nl","nz","ru","co.tk","tk","tv","us")

and what I would like to do, is:

from a length of 1 up to a length of 32 arrange the chars into a string, echoing the string, then going back to the beginning again. So eventually my browser would look something like this:

0.aero
1.aero
2.aero
3.aero
....
x.aero
y.aero
z.aero
-.aero
00.aero
01.aero
02.aero
....
za.aero
zb.aero
zc.aero
zd.aero
....
50x90zx908.aero
50x90zx909.aero
50x90zx90a.aero
50x90zx90b.aero
....
50x90zx910.aero
50x90zx911.aero
ect; ect;

How would I create for loops to do this? to include the $doma ones to the end as well each loop?

I know this is huge, but when I've got an idea I gotta try it ;)

Answer 1

If you really want to do this with for loops, then make 33 of them, one for each desired length (1-32) and one for the $doma array.

But I would not do it that way. Instead, observe that the desired combinations of the characters in the $char array actually form a tree. The root node represents the empty string. Each child node of the root represents a 1-character combination ("1", "2", "3", ...). Each child node of those nodes represent a 2-character combination that has the prefix of its parent node (so the children of the "1" node would all start with "1"), and so on. The leaves of the tree would be all 32-character combinations of the characters in $char. If there were only three characters, a, b, and c, it would look something like this:

You can then make a recursive function that implements a depth-first traversal of such a tree, and instead of generating the tree in memory and then printing it, you can just have the function output the contents of each node as it reaches it. Throw in a parameter that allows you to place a suffix after the node contents, and wrap the function in a loop that iterates through all elements in $doma, and you're done.

function f($array, $limit, $suffix, $prefix = "", $counter = 0)
{
    if ($counter > 0) {
        print "$prefix.$suffix\n";
    }

    if ($counter < $limit) {
        foreach ($array as $element) {
            f($array, $limit, $suffix, $prefix . $element, $counter+1);
        }
    }
}

$char=array("1","2","3","4","5","6","7","8","9","0","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","-");
$doma=array("aero","asia","biz","cat","com","coop","info","int","jobs","mobi","museum","name","net","org","pro","tel","travel","xxx","edu","gov","mil","co.uk","co.nr","co.au","au","ca","co.cc","cc","co","cn","co.jp","de","es","ie","in","it","jp","nl","nz","ru","co.tk","tk","tv","us");

foreach ($doma as $d) {
    f($char, 32, $d);
}

The order will not be exactly as you specified, but this ordering is logically consistent with the order of elements in the arrays and the depth-first traversal order.

Answer 2

The code basically treats the character combination like a base-35 number. It adds one each loop.

<?php

    $char=array("1","2","3","4","5","6","7","8","9","0","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","-");
    $doma=array("aero","asia","biz","cat","com","coop","info","int","jobs","mobi","museum","name","net","org","pro","tel","travel","xxx","edu","gov","mil","co.uk","co.nr","co.au","au","ca","co.cc","cc","co","cn","co.jp","de","es","ie","in","it","jp","nl","nz","ru","co.tk","tk","tv","us");

    $combo = array(0,0,0,0,0,0,0,0,0,0); //this stores the ten "digits" of the characters
    $pval = 9; //this is the active "place value", the one that you increment
    $list = "";

    for($i=0;$i<44;$i++) { //loops through doma
        for($j=0;$j<2758547353515625;$j++) { //loops through character combos, that long number is the permutations

            for($l=0;$l<10;$l++) { //loop displays combo
                $list .= $char[$combo[$l]];
            }
            $list .= "." . $doma[$i] . "<br/>"; //add combo to list

            /*This next part check to see if the active digit is 35. It is is, it sets it 
            equal to zero and looks to the digit on the left. It repeats this until it
            no longer finds a 35. This is like going from 09 to 10 in the decimal system. */
            if($combo[$pval] == 35) { 
                while($combo[$pval] == 35) {
                    $combo[$pval] = 0;
                    $pval--;
                }
            }
            $combo[$pval]++; //whatever digit it left on gets incremented.



            $pval = 9; //reset, go back to first place value
        }
        for($l=0;$l<10;$l++) {
            $combo[$l] = 0; //reset combo for the next top level domain
        }
    }
    echo $list; //print the compiled list.
    ?>