use strict;   # Always, for now.
use warnings; # Always, while developing code.
my %symbols;
open INFILE, "<mydata.txt" or die "Can't open infile.\n$!";
while ( my $key = <INFILE> ) {
    my $value;
    unless ( $value = <INFILE> ) { die "Uneven key/value pairs!"; }
    $value =~ s/^\s+|\s+$//g;
    $symbols{$key} = $value;
}

print "$_: $symbols{$_}\n" for keys %symbols;