die("Usage: $0 LENGTH") unless @ARGV;
my @alpha   = ( a .. z, A .. Z );
my $randstr = join '', map $alpha[rand @alpha], 0 .. shift;

print "random string: $randstr", $/;
[download]

_________
broquaint

Oh my god, it's so clear once you saw it !
I keep forgeting about those shortcuts like the range operator, I was starting to write:
my @alpa =('a','b',...) ;
BTW isn't a int missing before the rand @alpha ?
I mean, it works without it but it seems strange no?

BTW isn't a int missing before the rand @alpha ?
I mean, it works without it but it seems strange no?

Since arrays indices are integer based, so perl automagically converts the given float to an int. I should imagine it would be rather awkward accessing the 2.53815239812875th element of an array ;)
HTH

_________
broquaint

This works quite nicely as it's self documenting and the return can be assigned directly to a scalar.

#! perl -slw
use strict;

sub rndStr{local $"=''; "@_[map{rand$#_} 1 .. shift]"; }  

print rndStr 40, 'a'..'z';
print rndStr 40, 'A'..'Z';
print rndStr 40, 0..9;
print rndStr 40, 'a'..'z', 'A'..'Z', 0..9;

__END__
C:\test>212859
rxshjxkkgjqhyhukodujhmghpwujqteudxrvxsxo
MCRFGFETIDWEDHBWVSDKGJVMOEDEWKIJXRKAAGSQ
3288712881034147833223824725784363650780
EL0A5PsUCzPb8Sh3IyFGrCKElRPPeilXTPQDreKz

C:\test>
[download]

Okay this one is a little fancier. I knew that by asking a question (even this one wich is trivial) I would learn a lot!

Thanx BrowserUk

Sorry to admit that I don't understand the magic in it. Could you explain?

Sure. This is the same subroutine but opened out and using named parameters to explain the intermediate steps.

sub rndStr{
    # When an array is interpolated in a string $" is used to seperate
+ the values 
    # By setting it (locally) to '', we ensure that the string doesn't
+ have spaces or 
    # anything else inserted between the characters.
    local $" = ''; 
    
    my ( $len, @chars_to_pick_from) = @_;
    
    # @picks will end up with as many random values as requested.
    my @picks = map{ 
                    # Generate random numbers bewteen 0 and 
                    # the number of chars supplied to pick from
                    rand $#chars_to_pick_from
                    
                    # do it as many times as request
                   } 1 .. $length;
                   
    # Using an array slice interpolated in quotes to construct the str
+ing
    # @picks contains the random indices, the slice picks them out of 
+the
    # array of choices past in. The resultant string is returned as a 
+scalar.
    "@chars_to_pick_from[@picks]"; 
}
[download]

In the short version above, I'm just using the @_ array, (and shift to get the first parameter) and doing the whole thing in a single step rather than all seperated out.

Hope that helps.

---

Okay you lot, get your wings on the left, halos on the right. It's one size fits all, and "No!", you can't have a different color.
Pick up your cloud down the end and "Yes" if you get allocated a grey one they are a bit damp under foot, but someone has to get them.
Get used to the wings fast cos its an 8 hour day...unless the Govenor calls for a cyclone or hurricane, in which case 16 hour shifts are mandatory.
Just be grateful that you arrived just as the tornado season finished. Them buggers are real work.

OKay, I have another challenge then.
What about doing the same without using an array initialized with the chars we wanna pick ( ie (a..z) ? Would there be a solution?

Adjust the numbers and name to suit.

 sub rndlc{local$"=''; "@{[map{chr(97+int rand 26)} 1 .. shift]}" }

print rndlc 20;
hgvuemeeezgjwbzjmgezo
[download]

---

Okay you lot, get your wings on the left, halos on the right. It's one size fits all, and "No!", you can't have a different color.
Pick up your cloud down the end and "Yes" if you get allocated a grey one they are a bit damp under foot, but someone has to get them.
Get used to the wings fast cos its an 8 hour day...unless the Govenor calls for a cyclone or hurricane, in which case 16 hour shifts are mandatory.
Just be grateful that you arrived just as the tornado season finished. Them buggers are real work.

--
John.

Thanx :-).
PLaying golf? ok a little too trivial.