Is static_cast(-1) the right way to generate all-one-bits data without numeric_limits?

Question

I\'m writing C++ code in an environment in which I don\'t have access to the C++ standard library, specifically not to std::numeric_limits. Suppose I want to implem

Answer 1

Focusing on unsigned integral types, what do I put there? Specifically, is static_cast(-1) good enough

Yes, it is good enough.

But I prefer a hex value because my background is embedded systems, and I have always had to know the sizeof(T).

Even in desktop systems, we know the sizes of the following T:

uint8_t  allones8  = 0xff;
uint16_t allones16 = 0xffff;
uint32_t allones32 = 0xffffffff;
uint64_t allones64 = 0xffffffffffffffff;