use warnings;
use strict;
use Scalar::Util qw(looks_like_number);

while (<DATA>) {
    chomp;
    my $temp = $_;
    my $unit = lc chop $temp;
    if (looks_like_number($temp)) {
        print "temp = $temp : unit = $unit\n";
    }
}

__DATA__
55F
77c
foo
+0.4F