pack unpack incompatibility issue

How to identify incompatible use of pack and unpack. And how to fix it for following examples if they are incompatible uses. I want to use code around it in perl 5.22. This is present in perl 5.8 currently and working fine. I dont know if it will break or work when I upgrade perl to v5.22

pack("$L", unpack("$L", $_)
sprintf("%08x", unpack("N",function($relay))); 
push(@rv, join('.', unpack("CCCC", function($i)))); 
unpack("u", $len . $1 ); 
unpack("w*", $v); 
unpack("V", $v) == 1
unpack("x$start_offset x4 $L$L$L$L$S$S$L$L", $file); 
unpack("x$d_off $S/a", $file); 
unpack("H*", shift); 
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Re: pack unpack incompatibility issue by davido (Cardinal) on Aug 03, 2022 at 19:56 UTC
What is `$L`? Can't debug pack/unpack templates that we can't see. You should create a small segment of code starting with use strict, and ending with a __DATA__ tag that contains some sample data, and that demonstrates your packing and unpacking (which presumably aren't working as you intend), along with a good description of what you actually do intend. Self-contained. We should be able to run it and see the failure. Dave	[reply] [d/l]
Re: pack unpack incompatibility issue by ikegami (Patriarch) on Aug 03, 2022 at 20:33 UTC
I don't think any of them will have any issues except possibility differences in warnings for bad data. I know that `pack` changed how it handled some invalid inputs, but that's not relevant here. Upd: Looks like you found a possible source of problems: Incompatibility after perl 5.10 packing and UTF-8 strings	[reply] [d/l]
Re: pack unpack incompatibility issue by LanX (Saint) on Aug 03, 2022 at 20:54 UTC
> How to identify incompatible use of pack and unpack. by writing tests, see Test::More etc. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply]
Re: pack unpack incompatibility issue by afoken (Chancellor) on Aug 04, 2022 at 16:49 UTC
This seems to be closely related to Incompatibility after perl 5.10 packing and UTF-8 strings. Why did you create a new thread? Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply]