6.11.166 signbit Macro

Returns true if its argument is negative.

Include

<math.h>

Prototype

int signbit(floating-point x);

Argument

x

any floating-point number

Return Value

Returns true if its argument is negative; false otherwise.

Example

See the notes at the beginning of this chapter or section for information on using printf() or scanf() (and other functions reading and writing the stdin or stdout streams) in the example code.

#include <math.h>
#include <stdio.h>

int main(void)
{
  double x, y, z;
  int s;

  x = -5.0;
  y = 3.0;
  z = x / y;
  s = signbit(z);
  printf("The result of the division of %f by %f is %s\n", x, y, s ? "negative" : "positive");
}

Example Output

The result of the division of -5.000000 by 3.000000 is negative