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0 pointsjjtheblunt4y ago0 comments

UB = Undefined Behavior ?

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correct. In my experience a focus on UB (often actually said U.B.) tends to come from the C++ community, although a lot of it trickles down to the C community as well. I can recommend watching a few talks from C++ conferences. I especially enjoyed ones by Matt Godbolt, and Miro Knejp.

ncmncm4y ago

Not correct. Most UB is the same in C and C++. If you disallowed optimizations based on UB, it might have more effect on C++ programs, just because C++ tends to more deeply inlined abstractions that can benefit more from them. But those don't tend to need much attention. The cases people worry about are more common in C code, just because the concept of type is less important in C.

MobiusHorizons4y ago

How is this not correct? UB = Undefined Behavior.

Or are you saying that UB is not from the C++ community? That could certainly be true, I am just describing the situation as I see it where C++ disallows more types of casting or reinterpreting than C does (even if compilers allow it).

One salient example I heard was that the only way to legally read the bits of a float in C++ is to memcpy the float onto an integer type. whereas in C its legal (I believe by using a union).

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MobiusHorizons4y ago

ncmncm4y ago

MobiusHorizons4y ago

How is this not correct? UB = Undefined Behavior.

One salient example I heard was that the only way to legally read the bits of a float in C++ is to memcpy the float onto an integer type. whereas in C its legal (I believe by using a union).

2 more replies

j / k navigate · click thread line to collapse