I've seen lots of scripts where you can invoke them with flags followed by parameters (hopefully that's the right terminology)like this:

./myscript.pl -a param_a -b param_b -d param_d -c param_c input1 input
+2
[download]

The problem is I don't know how to take that input and use it in the script. I know how to use @ARGV, but that would mean no flags and the params would have to be in the correct and same order every time.

The only solution I can think of right now is to loop through @ARGV.
Check if the value starts with a "-"
if it does then figure out which flag it is and assign the correct variable with the next value in @ARGV
if the value doesn't start with a "-" and the previous value doesn't either, then take that as normal input and proceed with the script.
if the value doesn't start with a "-" but the previous value does, then treat it as the value for that flag

Something about this just says to me there has to be a better way. Is there?

Thanks in advance

Edit: Big thanks to borisz for the first, most concise, and most useful answer. Thanks to everyone else as well.