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The C23 edition of Modern C

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397 points bwidlar | 1 comments | 15 Oct 24 16:06 UTC | HN request time: 0s | source
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ralphc ◴[15 Oct 24 18:30 UTC] No.41851601[source]▶
How does "Modern" C compare safety-wise to Rust or Zig?
replies(4): >>41852048 #>>41852113 #>>41852498 #>>41856856 #
renox ◴[15 Oct 24 19:11 UTC] No.41852048[source]▶
You'd be surprised: Zig has one UB (Undefined Behaviour) that C doesn't have!

In release fast mode, unsigned overflow/underflow is undefined in Zig whereas in C it wraps.

:-)

Of course C has many UBs that Zig doesn't have, so C is far less safe than Zig, especially since you can use ReleaseSafe in Zig..

replies(2): >>41852363 #>>41852615 #
secondcoming ◴[15 Oct 24 20:11 UTC] No.41852615[source]▶
Does C automatically wrap? I thought you need to pass `-fwrapv` to the compiler to ensure that.
replies(3): >>41852833 #>>41852848 #>>41852877 #
renox ◴[15 Oct 24 20:38 UTC] No.41852848{3}[source]▶
-fwrapv is for signed integer overflow not unsigned.
replies(1): >>41853085 #
1. sp1rit ◴[15 Oct 24 21:02 UTC] No.41853085{4}[source]▶
Yes, as unsigned overflow is fine by default. AFAIK the issue was originally that there were still machines that used ones complement for describing negative integers instead of the now customary twos complement.