#!/usr/bin/perl -w

$foo = 0;

# not a good way to open a file, 
# should be open FOO, "<$path/$file"
# also print after die not needed
open (VECTORS, "vectors") or die print "Cannot open 'vectors' file: $!\n";

while ($line = <VECTORS>) {
    if ($line =~ /\d/) {
        chomp $line;
        ($vectorA[$foo], $angleA[$foo], $vectorB[$foo], $angleB[$foo]) = split " ", $line, 4;
        
        # debugging print
        print"file input $foo: $vectorA[$foo], $angleA[$foo], $vectorB[$foo], $angleB[$foo]\n";
        
        ++$foo;
    }
}

# this is wrong $foo is 1 as you incremented it
# at the end of the loop, so when you hit the last
# element you increment $foo 1 too much and set
# $max_vector to 1 to0 much
$max_vectors = $foo;

# debugging print
print "\$max_vectors: $max_vectors\n";

for ($foo = 0; $foo <= $max_vectors; ++$foo) {
 
    # debugging print
    print"\$foo $foo\n";

    # this should be = for first assignment not +=
    $X[$foo] += ($vectorA[$foo] * cos($angleA[$foo]));
    $X[$foo] += ($vectorB[$foo] * cos($angleB[$foo]));
}

# this is another loop just like the one above
# why not put the two statements here with the two above?
# and just have the one loop
# this is also the longhand++ loop syntax
for ($foo = 0; $foo <= $max_vectors; ++$foo) {

    # debugging print
    print"\$foo $foo\n";
 
    # this should be = for first assignment not +=
    $Y[$foo] += ($vectorA[$foo] * sin($angleA[$foo]));
    $Y[$foo] += ($vectorB[$foo] * sin($angleB[$foo]));
}

# Must do more stuff here, ie. finish and convert to degrees after sin() and cos()

foreach $X (@X) {
    print "$X\n";
}

print "\nblah\n\n";

foreach $Y (@Y) {
    print "$Y\n";
}

#!/usr/bin/perl -w

use strict;
my (@vectorA, @angleA, @vectorB, @angleB, @X, @Y);

open (VECTORS, "<c:/vectors.txt") or die "Oops $!\n";

my $i = -1;
while (my $line = <VECTORS>) {
    next unless $line =~ /\d/;
    $i++;
    ($vectorA[$i], $angleA[$i], $vectorB[$i], $angleB[$i]) = split/\s+/,$line;
}
die "Sorry, no data!\n" if $i == -1;
my $max_vectors = $i;

for (0..$max_vectors) {
    $X[$_] = ($vectorA[$_] * cos($angleA[$_]));
    $X[$_] += ($vectorB[$_] * cos($angleB[$_]));
    $Y[$_] = ($vectorA[$_] * sin($angleA[$_]));
    $Y[$_] += ($vectorB[$_] * sin($angleB[$_]));
}

# Must do more stuff here, ie. finish and convert to degrees after sin() and cos()

print "$_\n" for @X;

print "\nblah\n\n";

print "$_\n" for @Y;