signbit - cppreference.com (original) (raw)

| | | | | ----------------------------------------------------- | | ----------- | | #define signbit( arg ) /* implementation defined */ | | (since C99) |

Determines if the given floating-point number arg is negative. The macro returns an integral value.

[edit] Parameters

arg	-	floating-point value

[edit] Return value

Nonzero integral value if arg is negative, 0 otherwise.

[edit] 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.

[edit] Example

#include <math.h> #include <stdio.h> int main(void) { printf("signbit(+0.0) = %d\n", signbit(+0.0)); printf("signbit(-0.0) = %d\n", signbit(-0.0)); }

Possible output:

signbit(+0.0) = 0 signbit(-0.0) = 128

[edit] References