Select Code to Download

use Getopt::Long (); 

...

print("\$opt_float = ", defined($opt_float) ? $opt_float : "[undef]", 
+"\n");
print("\@ARGV      = ", join(' ', @ARGV), "\n");

>perl 551380.pl -float 1.3
$opt_float = 1.3
...
>perl 551380.pl -float abc
$opt_float = [undef]
@ARGV      = -float abc