if ($num % 2 == 0) {
    #even
}
else {
    #odd
}

##</code><code>##

while(!eof(FILE1) && !eof(FILE2) {
   my $file1 = <FILE1>;
   my $file2 = <FILE2>;
}

##</code><code>##

my @eol = ("\n","\t","\r"); # etc, etc
while(<FILE>) {
    local $/ = shift @eol;
    my $line = <FILE>;
}