We don't bite newbies here... much PerlMonks

### Re^2: finding number of contiguous letters

 on May 23, 2007 at 16:13 UTC ( #617055=note: print w/replies, xml ) Need Help??

in reply to Re: finding number of contiguous letters
in thread finding number of contiguous letters

Far better solutions have been presented, but here is another. I was considering how to do if we had tail recursion. I had been hoping to place all code in the argument list...

```sub parts {
my ( \$cnt, \$ra_out, \$ra_val, \$ra_in ) = @_;
if( \$#\$ra_val != \$cnt ){ #working array not full
if( \$#\$ra_in > -1 ){ #fill it up
push(@\$ra_val, shift(@\$ra_in));
parts( \$cnt, \$ra_out, \$ra_val, \$ra_in );
} else {             #done with list
return;
}
} else {
+ut array, joined ltr string
shift(@\$ra_val);                                  #rip off fir
+st ltr
push(@\$ra_val, shift(@\$ra_in)) if(\$#\$ra_in > -1); #add new ltr
+, if any remaining
parts( \$cnt, \$ra_out, \$ra_val, \$ra_in );
}
}
my @in  = split( '', "computer" ); # input array of individual letters
my @out;                           # out array of strings each of \$cnt
++1 ltrs
my @val;                           # working array of individual lette
+rs, \$cnt+1 elements
parts( 2, \@out, \@val, \@in );
#results in @out

..Otto

Replies are listed 'Best First'.
Re^3: finding number of contiguous letters
by blazar (Canon) on May 23, 2007 at 20:03 UTC
I was considering how to do if we had tail recursion.

We do have tail recursion. Well not really: sort of. That's courtesy of magic goto: but then of course one has to explicitly make use of it, not that TR is automatically recognized, which is what you clearly meant.

Blazar,

You got me thinking, I'm going to play with this some more, but first... are sub arguments, ie a list, evaluated in order?

For example suppose a list is composed of ( <a>, <b>, <c> )where each of the a, b, c are one or more sub calls that may mutate some value, which may be used by others further down the list, will the list values be evaluated in order of a, b, c, or is it undefined?

I quickly looked at the sub function and the comma operator which did not shed any light, or at least I didn't see it...

.. Otto

For example suppose a list is composed of ( <a>, <b>, <c> ) where each of the a, b, c are one or more sub calls that may mutate some value, which may be used by others further down the list, will the list values be evaluated in order of a, b, c, or is it undefined?

IIUC, why don't you find out yourself?

```#!/usr/bin/perl -l

use strict;
use warnings;

BEGIN {
my \$foo;
sub foo () { \$foo }
for my \$n (qw/a b c d e f/) {
no strict 'refs';
*\$n = sub () { warn \$n; \$foo++ };
}
}

my \$arr=(a,b,c,d,e,f);
print foo, \$arr;

__END__

Create A New User
Node Status?
node history
Node Type: note [id://617055]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others lurking in the Monastery: (6)
As of 2020-10-27 21:40 GMT
Sections?
Information?
Find Nodes?
Leftovers?
Voting Booth?
My favourite web site is:

Results (258 votes). Check out past polls.

Notices?