For a start put:

use strict;
use warnings;
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at the start of your script.

By the time you have removed all the warnings and errors your problem will have changed!

Some sample data would help. You may like to use <DATA> rather than <FILE> and put a __DATA__ section at the end of your script.

Update: Add sample data comment

Well, at least use strict; I would think the warnings part would be covered by the #!/usr/bin/perl -w line.

    -Bryan

In this case, I'd put use warnings anyway. Note that OP's shabang does not start from the very first character in the script, because there are some lines of comment before (and an empty one, too). Thus, the -w switch is likely to be ignored in this case.

Flavio
perl -ple'$_=reverse' <<<ti.xittelop@oivalf

Don't fool yourself.

My eye skipped over it. Can't even blame coffee lack :^(

---

Perl is Huffman encoded by design.

I turned the commet #'s into my's in your "declaration" block, added declarations for $line (before the input loop) and $i (in sub check_data) and changed the my $p_e = 0, $p_t = 0; line into two "my" lines. Running the result against a data file containing:

0-0->0-1
0-0->0-2
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gave the following output:

I don't know what it means, but the second loop sure is running.

you guys... Rock!

Thanks for all the re's in so short a time - I was thinking I'd be lucky to get one or two by the end of the day:)

I've added "use strict;" and "use warnings;" and have declared all my global vars "our", all local block vars "my" etc..

Grandfather is correct with his sample of my input - here is an extended snippit for further clarity:


1-1
1-2
1-3
1-4

1-2->2-1
1-4->3-4
 
2-1
2-2
2-3
2-4

2-2->1-3
2-4->3-3

3-1
3-2
3-3
3-4

3-2->2-3
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the /\d-\d/ lines are individual events to be unshift'd to (and later pop'd from) the @p_s 2D-array, and /\d-\d->\d-\d/ are dependencies to be added to the %sender and %receiver hashes...

Currently Eclipse is throwing the following error:

Use of uninitialized value in array element at C:/Lamport.pl line 69.

The error refers specifically to the following lines:

foreach $pid (@p_s) 
{
 #...rest of scheduler loop
}
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I ran this loop alone with only a print "$pid\n"; statement and got a set of ARRAY(0x186b8f8) values for $pid. I think that I've been to liberal in my use of foreach() and will restructure this more intelligently.

I'm curious why the loop seems to execute for Grandfather though...? Perhaps it is because his test case was limited to a single process/stack....

Any suggestions on an good way to iterate through the first level (@p_s[]) of a 2D array? The trick is that I need to get an index for all of the @p_s[$pid][#pop'd] stacks one at a time, (each $pid stack is pop'd once one level at a time then the process is repeated)? I think I can do this with a regular while loop provided that I count the number of processes while parsing the input, however is there a more elegant way of doing this?

Many Thanks, Thanks and Thanks again to all of you for the quick responses & insight - ya'll have helped me immensely already.

This comment has nothing to do with your difficulties (except that we'll spot the source of one), just some notes on more idiomatic perl for your read loop.

First the preliminaries,

#!/usr/bin/perl
use warnings;
use strict;

our (%sender, %receiver, @p_s};
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You open a data file from a path given on the command line. There is an implicit mechanism in perl - the diamond operator with default argument - which does that, allowing you to skip opening the file. You were slurping the file, but that makes your loop run only once, with match only catching the first instance. Let's read it line by line with a while loop, and accept the default loop variable, $_, which allows us to use default match bindings and argument to chomp.

while (<>) {
    chomp;
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    if (m/(\d-\d)->(\d-\d)/) {
        $sender{$1} = $2;
        $receiver{$2} = $1;
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        warn "enter ",
            "$sender{$1}->$receiver{$2} ",
            "in dependency hashes\n";
    }
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        unshift @{$p_s[$2]}, $1;
        warn "unshift $1 onto process array\n";
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    }
    else {
        warn "unmatched line: $_\n";
    }
}
# . . .
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Using the empty diamond has two effects which may not suit you. First, every file listed on the command line will be read and parsed in order. Second, if none are listed there the diamond will look at STDIN, either a pipe or the terminal. Both are useful if you design for them, otherwise they can be a source of surprise.

The scope of variables defined with my ends at the next closing brace. The scope of variables defined 'on the fly' (which is forbidden with use strict) ends at the end of the file.

> Will vars declared on the fly in the first loop be visible in the second loop?
Yes.

> Perl (with no main block)
It is good practice to put all your top-level code in a sub main($) { .. } and put main(\@_); at the end of your file; precisely because it separates the scope of variables local to the concepual or actual main from the purposefully global variables (which I assume you want to use to communicate between the loops).

What does "I'm having issues getting the script to run" mean? What is the exact error message?

In order to simply try your program, an input file would be needed, consider providing an example.

Also, your program is a bit long for debugreading, please try to reduce your problem by elimination.

Finally, please read How do I post a question effectively?