signbit
From cppreference.com
| Defined in header <math.h>
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| #define signbit(arg) /* implementation defined */ |
(since C99) | |
Determines if the given floating point number arg is negative. The macro returns an integral value.
Parameters
| arg | - | floating point value |
Return value
Nonzero integral value if arg is negative, 0 otherwise.
Notes
This macro detects the sign bit of zeroes, infinities, and NaNs. Along with copysign, this macro is one of the only two portable ways to examine the sign of a NaN.