If the implementation supports any of the following
ISO 60559
types as an extended floating-point type, then:
-
the corresponding macro is defined as
1
to indicate support,
-
the corresponding
floating-point literal
suffix is available, and
-
the corresponding type alias 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
#include <stdfloat>
#if __STDCPP_FLOAT64_T__ != 1
#error "64-bit float type required"
#endif
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