Fixed-size floating point types

c++ c boost floating-point
Pietro picture Pietro · Mar 26, 2010 · Viewed 44k times · Source

In the stdint.h (C99), boost/cstdint.hpp, and cstdint (C++0x) headers there is, among others, the type int32_t.

Are there similar fixed-size floating point types? Something like float32_t?

Answer

Stephen Canon picture Stephen Canon · Mar 26, 2010

Nothing like this exists in the C or C++ standards at present. In fact, there isn't even a guarantee that float will be a binary floating-point format at all.

Some compilers guarantee that the float type will be the IEEE-754 32 bit binary format. Some do not. In reality, float is in fact the IEEE-754 single type on most non-embedded platforms, though the usual caveats about some compilers evaluating expressions in a wider format apply.

There is a working group discussing adding C language bindings for the 2008 revision of IEEE-754, which could consider recommending that such a typedef be added. If this were added to C, I expect the C++ standard would follow suit... eventually.

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