std::signbit
Defined in header <cmath>
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| (1) | ||
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bool signbit(
float num )
;
bool signbit( double num ); |
(since C++11) (until C++23) |
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constexpr
bool signbit(
/*floating-point-type*/ num )
;
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(since C++23) | |
SIMD overload (since C++26) |
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Defined in header <simd>
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template
<
/*math-floating-point*/ V >
constexpr
typename
/*deduced-simd-t*/
<V>
::
mask_type
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(S) | (since C++26) |
Defined in header <cmath>
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template
<
class Integer >
bool signbit( Integer num ) ; |
(A) | (since C++11) (constexpr since C++23) |
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S) The SIMD overload performs an element-wise
std::signbit on v_num.
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(since C++26) |
Parameters
| num | - | floating-point or integer value |
| v_num | - | a data-parallel object of std::basic_simd specialization where its element type is a floating-point type |
Return value
[
0
,
v_num.size()
)
Notes
This function detects the sign bit of zeroes, infinities, and NaNs. Along with std::copysign, std::signbit
The additional overloads are not required to be provided exactly as (A). They only need to be sufficient to ensure that for their argument num of integer type, std::signbit(num) has the same effect as std:: signbit ( static_cast < double > (num) )
Example
#include <cmath> #include <iostream> int main() { std::cout << std::boolalpha << "signbit(+0.0) = " << std::signbit(+0.0) << '\n' << "signbit(-0.0) = " << std::signbit(-0.0) << '\n' << "signbit(+nan) = " << std::signbit(+NAN) << '\n' << "signbit(-nan) = " << std::signbit(-NAN) << '\n' << "signbit(+inf) = " << std::signbit(+INFINITY) << '\n' << "signbit(-inf) = " << std::signbit(-INFINITY) << '\n'; }
Output:
signbit(+0.0) = false signbit(-0.0) = true signbit(+nan) = false signbit(-nan) = true signbit(+inf) = false signbit(-inf) = true
See also
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(C++11)(C++11)
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absolute value of a floating point value (|x|) (function) |
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(C++11)(C++11)(C++11)
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copies the sign of a floating point value (function) |
C documentation for signbit
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