in reply to Generating a random string of chars, easily.

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 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.

Replies are listed 'Best First'.
Re: Re: Generating a random string of chars, easily.
by Sihal (Pilgrim) on Nov 14, 2002 at 16:46 UTC
    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
[reply]
Re: Re: Generating a random string of chars, easily.
by Sihal (Pilgrim) on Nov 14, 2002 at 16:52 UTC
    Sorry to admit that I don't understand the magic in it. Could you explain?
[reply]

      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.

[reply]
[d/l]
        Woah
        first I didnt know about slices ( didnt need them yet) and then didnt know about quoting an array ( even if I now realize that I use it daily) .
        Thanks for the good lesson.
        Though the one from broquaint is the most pertninent choice (in my case) .
[reply]
Re: Re: Generating a random string of chars, easily.
by Sihal (Pilgrim) on Nov 14, 2002 at 18:54 UTC
    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?
[reply]

      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.

[reply]
[d/l]
        I say bravo lol
        but this was simple. okay now you tell me if you can find another way, and i ll try to find what it is. as an exercise.
[reply]

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