Hi. I am trying to create a program to parse a certain file. In that file is a text model of a circuit, and I want to produce a data structure that can be given to another program I've written which produces the equivalent capacitance of the circuit (so far the circuit consists solely of a batery, wire, and multiple capacitors). The data structure I want to make looks like this

    # $Circ->[id][lead][index] = otherID
    # id is capacitor's index
    # lead == 0 means positive
        #         and lead == 1 means negative
    # index is arbitrary (each cap may point to
        #         several other capacitors)
    # otherID represents the cap's index that is
        #         being pointed to
[download]

So a sample circuit might look like this:

    #    B+..............
    #    -      .       .
        #       .     C1      C2
    #    .      .       .
    #    .      .       .
    #       .      .........
    #       .         C3
    #       .          .
    #       ............

    $Circ->[0][0][0] = 1;  # Cap[0]'s positive lead connects to Cap[1]
    $Circ->[0][1][0] = 1;  # Cap[0]'s negative lead goes to Cap[1]
    $Circ->[0][1][1] = 2;  # Cap[0]'s negative lead goes to Cap[2]
    
    $Circ->[1][0][0] = 0;  # etc.
    $Circ->[1][1][0] = 0;
    $Circ->[1][1][1] = 2;

    $Circ->[2][0][0] = 0;  # etc.
    $Circ->[2][0][1] = 1;  # etc.
    $Circ->[2][1]    = (); # not pointing to anything
[download]

The code I have so far doesn't seem to work. It is recursive, and I was a little worried my algorithm might become circular and never ending. Unfortunately, it seems to only go through the first row of data. My code is below, along with the sample file that I read in. Any help is greatly appreciated. Thanks.

# read in file, make circuit ...

use Data::Dumper;

#               012345678901  <--(i)-->
#         0    B+.....1....
#    |         1    -          .
#   (j)         2    .          .
#    |         3    .          .
#         4    .........2..

open (CIRC, "circ.txt");

$cnt = 0;
$i = 0; $j = 0;
$on_cap = undef;

while (<CIRC>) { # put elements of circuit into m-d array
    last if $_ =~ /=+/;
    chomp;
    $i = 0;
    for $char (split //, $_) { push @{$Circ->[$i++][$j]}, $char }
    $j++;
}

$i = 1; $j = 0;

if ($Circ->[0][0][0] eq 'B' && $Circ->[1][0][0] eq '+' && $Circ->[0][1
+][0] eq '-') {
    $Circ->[0][0][0] = '.';
    $Circ->[1][0][0] = '.';
    $Circ->[0][1][0] = '.';
} else { die "malconfigured circuit" }

$on_i = $i; $on_j = $j;

&make_circ ($i,$j);

sub make_circ {
    # count caps, make sure > 1
    for $x (0..scalar @$Circ-1) {
        for $y (0..scalar @{$Circ->[$x]}-1) {
            if ($Circ->[$x][$y][0] =~ /\d/) { $cnt++ }
        }
    }

    goto END if $cnt <= 1; $cnt = 0;

    $i = $_[0]; $j = $_[1];

    goto END if $ignore[$i][$j];

    $looked_at[$i][$j] = 1;

    Iter ($i,$j);

    END:
}

sub Iter {
    $i = $_[0]; $j = $_[1];

    $val = LookAt ($i,$j);

    if ($val == 0) {
        if ($j-1 > 0) { Iter ($i,$j-1) unless $looked_at[$i][$j-1] }
        if ($j+1 < scalar @{$Circ->[$i]}-1) { Iter ($i,$j+1) unless $l
+ooked_at[$i][$j+1]}
        if ($i-1 > 0) { Iter ($i-1,$j) unless $looked_at[$i-1][$j] }
        if ($i+1 < scalar @$Circ-1) { Iter ($i+1,$j) unless $looked_at
+[$i+1][$j] }
    }
    elsif ($val == 1) {
        $ignore[$i][$j] = 1;
    }
    else {
        for $idx (0..$#looked_at) {
            for (0..scalar @{$looked_at[$idx]}-1) {
                $looked_at[$idx][$_] = 0;
            }
        }
    }

    if (defined $on_cap) {
        for $id (@{$circuit->[$on_cap][0]}) {
            if (defined $id) { $circuit->[$id][0] = $on_cap }
        }
        # when done with Cid, replace with '.'
        $Circ->[$on_i][$on_j] = ['.'];
        $on_cap = undef;
        make_circ ($i,$j);
    }
}

sub LookAt {
    $l_i = $_[0];
    $l_j = $_[1];

    $cell = $Circ->[$l_i][$l_j];

    if ($cell->[0] eq '.') { $ret = 0 }
    elsif ($cell->[0] =~ /(\d)/) {
        if (defined $on_cap) {
            push @{$circuit->[$on_cap][0]}, $1;
            $ret = 2
        } else {
            $on_cap = $1;
            $on_i = $l_i; $on_j = $l_j;
            $ret = 0;
        }
    }
    else { $ret = 1 }

    return $ret;
}

# AND THE FILE
# CIRC.TXT

B+.....1....
-          .
.          .
.          .
.........2..
============
1:5
2:6
[download]

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