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Tell me the truth ... (piefed.jeena.net)

submitted 3 weeks ago by cm0002@lemmy.world to c/programmer_humor@programming.dev

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[-] savedbythezsh@sh.itjust.works 14 points 3 weeks ago

Are you telling me that no compiler optimizes this? Why?

[-] Anders429@programming.dev 35 points 3 weeks ago

It would be slower to read the value if you had to also do bitwise operations to get the value.

But you can also define your own bitfield types to store booleans packed together if you really need to. I would much rather that than have the compiler do it automatically for me.

[-] timhh@programming.dev 24 points 3 weeks ago

Well there are containers that store booleans in single bits (e.g. std::vector<bool> - which was famously a big mistake).

But in the general case you don't want that because it would be slower.

[-] ethancedwards8@programming.dev 7 points 3 weeks ago

Why is this a big mistake? I’m not a c++ person

[-] bitcrafter@programming.dev 5 points 3 weeks ago

The mistake was that they created a type that behaves like an array in every case except for bool, for which they created a special magical version that behaves just subtly different enough that it can break things in confusing ways.

[-] ethancedwards8@programming.dev 2 points 3 weeks ago

Could you provide an example?

[-] timhh@programming.dev 1 points 2 weeks ago

The biggest problem is that each element doesn't have a unique memory address; iterators aren't just pointers.

[-] gamer@lemm.ee 5 points 3 weeks ago* (last edited 3 weeks ago)

Consider what the disassembly would look like. There's no fast way to do it.

It's also unnecessary since 8 bytes is a negligible amount in most cases. Serialization is the only real scenario where it matters. (Edit: and embedded)