std::signbit
From cppreference.com
| Defined in header <cmath>
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| bool signbit( float arg ); |
(1) | (since C++11) |
| bool signbit( double arg ); |
(2) | (since C++11) |
| bool signbit( long double arg ); |
(3) | (since C++11) |
| bool signbit( Integral arg ); |
(4) | (since C++11) |
1-3) Determines if the given floating point number
arg is negative.4) A set of overloads or a function template accepting the
from argument of any integral type. Equivalent to (2) (the argument is cast to double). Parameters
| arg | - | floating point value |
Return value
true if arg is negative, false otherwise
Notes
This function detects the sign bit of zeroes, infinities, and NaNs. Along with std::copysign, std::signbit is one of the only two portable ways to examine the sign of a NaN.
Examples
Run this code
#include <iostream> #include <cmath> int main() { std::cout << std::boolalpha << "signbit(+0.0) = " << std::signbit(+0.0) << '\n' << "signbit(-0.0) = " << std::signbit(-0.0) << '\n'; }
Output:
signbit(+0.0) = false signbit(-0.0) = true
See also
| absolute value of a floating point value (|x|) (function) | |
| (C++11) |
copies the sign of a floating point value (function) |
| C documentation for signbit
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