Question

In C, should I use the pre-defined (I think as macros) types such as int64_t, uint8_t, time_t, and size_t, or should I stick with long long, unsigned char, unsigned long, etc?

Answer 1

Use the macro types if you're looking for specific sizes. long long can mean a different size across different platforms, while int64_t is defined as a 64-bit integer type.

That said, I believe long long is a *minimum* of 64 bits, due to its definition in the standard. So int64_t is explicitly exactly 64 bits, while long long may be more.