Fixed width floating-point types (since C++23)

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Utilities library

Language support Type support (basic types, RTTI) Library feature-test macros (C++20) Dynamic memory management Program utilities Coroutine support (C++20) Variadic functions is_constant_evaluated (C++20) is_within_lifetime (C++26) initializer_list (C++11) source_location (C++20) Three-way comparison three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20)   is_eqis_ltis_lteq (C++20)(C++20)(C++20)   is_neqis_gtis_gteq (C++20)(C++20)(C++20)

General utilities Date and time Function objects Formatting library (C++20)   bitset hash (C++11) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator>    rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)   cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23) Elementary string conversions to_chars (C++17) from_chars (C++17) chars_format (C++17) to_chars_result (C++17) from_chars_result (C++17)

 

Type support

Basic types
Fixed width integer types (C++11)
Fixed width floating-point types (C++23)
ptrdiff_t size_t max_align_t (C++11)     byte (C++17)	nullptr_t (C++11) offsetof NULL
Numeric limits
numeric_limits
C numeric limits interface
Runtime type information
type_info type_index (C++11)	bad_typeid bad_cast

 

If the implementation supports any of the following types, the corresponding macro is predefined, floating-point literal suffix is available, and the typedef name is provided:

Type name Defined in header <stdfloat>	Literal suffix	Predefined macro	C language type	type properties
				bits of storage	bits of precision	bits of exponent	max exponent
std::float16_t	f16 or F16	__STDCPP_­FLOAT16_­T__	_Float16	16	11	5	15
std::float32_t	f32 or F32	__STDCPP_­FLOAT32_­T__	_Float32	32	24	8	127
std::float64_t	f64 or F64	__STDCPP_­FLOAT64_­T__	_Float64	64	53	11	1023
std::float128_t	f128 or F128	__STDCPP_­FLOAT128_­T__	_Float128	128	113	15	16383
std::bfloat16_t	bf16 or BF16	__STDCPP_­BFLOAT16_­T__	(n/a)	16	8	8	127

Notes

The type std::bfloat16_t is known as Brain Floating Point.

Unlike the fixed width integer types, which may be aliases to standard integer types, the fixed width floating-point types must be aliases to extended floating point types (not float / double / long double).

Example

Run this code

#include <stdfloat>
 
int main()
{
    std::float64_t f = 0.1f64;
}

References

• C++23 standard (ISO/IEC 14882:2024):

• 6.8.3 Optional extended floating-point types [basic.extended.fp]

See also

• Fundamental types