Safe way to get number of bytes for a data type in C++

Question

I'm using C++11 and higher and I was asking myself if it is safe to get the number of bytes required for a datatype like std::uint16_t to send over length agnostic protocols. More precise is it safe to call sizeof(std::uint16_t) and can I assume that this is always 2? What about std::int16_t?

Answer 1

Safe way to get number of bytes for a data type in C++

That would be the sizeof operator.

More precise is it safe to call sizeof(std::uint16_t) and can I assume that this is always 2?

No. You can only rely on that when byte is 8 bits.

What about std::int16_t?

Same.

---

For network communication, what you may need to know is how many octets a type is. That can safely be calculated like this: sizeof(std::uint16_t) * (CHAR_BIT / 8), and will be 2 for std::uint16_t. Note that not all systems necessarily have the std::uint16_t type.