strict aliasing

[bold imp]

is this considered UB (assume sizeof(float) == sizeof(int))

int fn(float f) {
  return *((int*)((char*) &f));
}

[cinder elm]

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[hushed holly]

yes

[bold imp]

so it doesnt matter if i do it through a char *?

aka theres no legal way to do this ?

[hushed holly]

it's ultimately through int*, the step in the middle is pointless

what you're doing is accessing an object of type float through a pointer to int, that's never valid

[bold imp]

alright thx

[hushed holly]

std::bit_cast, std::memcpy

[bold imp]

memcpy would make it legal ?

[hushed holly]

yeah

[bold imp]

because i do it byte per byte ?

[hushed holly]

it might also be valid to use std::start_lifetime_as to begin the lifetime of an int in the storage of the float

[hushed holly]

yeah, you're allowed to read and write to object bytes of trivial types however you like

oh wait this question is for C, so no std::start_lifetime_as then I guess

so just memcpy and union then, where union is only a valid approach in C

[bold imp]

neat

thank you

!solved