Insufficent data.

You are right though. I want to step through every possible combination given the integers 0 through 9 from 4 to 6 digits long. I guess a better list would be:

0000
0001
0002
0003
0004
0005
0006
0007
0008
0009
0010
0011
0012
....
....
9999 # Once the script maxes each place digit at 9
00000 # it adds another place digit and starts over.
00001
.....
.....
99999 # Same here when all 5 digits are maxed at 9 it
000000 # adds a 6th digit and starts over.
000001
......
......
999999

For that case you can get as simple as

for( map '0'x$_ .. '9'x$_, 4..6 ) {
[download]

but that chews up quite a chunk of memory. You can use tons less memory with something like

    for my $len ( 4 .. 6 ) {
        my $pat = '0' x $len;
        while( $len == length $pat ) {
            # ...
            $pat++;
        }
    }
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But, of course, that won't help much if you hope to change your list of characters to something other than 0..9.

Algorithm::Loops would probably be quite helpful for this if you do hope to use characters other than digits. But I think I'll not code an example for that at this point, though it can be done fairly simply (or more complexly if you want a single iterator, for example).

- tye        

Mostly springing from tye's solution, but it avoids the memory growth.

$\ = "\n";
for $n ( 4 .. 6 ){ 
    print for '0' x $n .. '9' x $n;
}
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And if you needed different 'digits' then

$\ = "\n";
my @digits = 'a' .. 'j';

for my $n ( 4 .. 6 ) {
    print @digits[ split '', $_ ] 
        for '0' x $n .. '9' x $n;
}
[download]

---

Examine what is said, not who speaks.

"Efficiency is intelligent laziness." -David Dunham
"Think for yourself!" - Abigail
"Memory, processor, disk in that order on the hardware side. Algorithm, algoritm, algorithm on the code side." - tachyon

This is a class assignment, isn't it?
"Even if you are on the right track, you'll get run over if you just sit there." - Will Rogers