How do I use decimal (float) in C++?

Question

According to IEEE 754-2008 there are

There are three binary floating-point basic formats (which can be encoded using 32, 64 or 128 bits) and two decimal f

Answer 1

C++ does not provide decimal types; the only floating point types are float, double and long double.

Neither does C++ specify that these use IEEE754 representations, or that they have any particular size. The only requirement is that double provides at least as much precision as float, and that long double provides at least as much precision as double.