[stdfloat.syn]

# 17 Language support library [[support]](./#support)

## 17.4 Arithmetic types [[support.arith.types]](support.arith.types#stdfloat.syn)

### 17.4.2 Header <stdfloat> synopsis [stdfloat.syn]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/support.tex#L2076)

The header [<stdfloat>](#header:%3cstdfloat%3e "17.4.2 Header <stdfloat> synopsis [stdfloat.syn]") defines type aliases for
the optional extended floating-point types that are specified in[[basic.extended.fp]](basic.extended.fp "6.9.3 Optional extended floating-point types")[.](#1.sentence-1)

[🔗](#header:%3cstdfloat%3e)

namespace std {#if defined(__STDCPP_FLOAT16_T__)using float16_t = *implementation-defined*; // see [[basic.extended.fp]](basic.extended.fp "6.9.3 Optional extended floating-point types")#endif#if defined(__STDCPP_FLOAT32_T__)using float32_t = *implementation-defined*; // see [[basic.extended.fp]](basic.extended.fp "6.9.3 Optional extended floating-point types")#endif#if defined(__STDCPP_FLOAT64_T__)using float64_t = *implementation-defined*; // see [[basic.extended.fp]](basic.extended.fp "6.9.3 Optional extended floating-point types")#endif#if defined(__STDCPP_FLOAT128_T__)using float128_t = *implementation-defined*; // see [[basic.extended.fp]](basic.extended.fp "6.9.3 Optional extended floating-point types")#endif#if defined(__STDCPP_BFLOAT16_T__)using bfloat16_t = *implementation-defined*; // see [[basic.extended.fp]](basic.extended.fp "6.9.3 Optional extended floating-point types")#endif}