PHP: going through all possible combinations

[unbound]

How can I go through all possible combinations from A to Z with f.e. 4 letters? It should print something like this:

aaaa
aaab
aaac
aaad
aaae

etc.

So how can I do this with PHP? Or is it even possible?

[jumpenjuhosaphat]

Sure it's possible, one way to do it, probably the simplest, is to nest 4 loops.

for($a=97; $a<123; $a++){
for($b=97; $b<123; $b++){
for($c=97; $c<123; $c++){
for($d=97; $d<123; $d++)
 {
  echo chr($a).chr($b).chr($c).chr($d);
}}}}

[unbound]

Okay, thanks.