ilogb, ilogbf—get exponent of floating-point numberSynopsis
#include <math.h> int ilogb(double val); int ilogbf(float val);
Description
All nonzero, normal numbers can be described as m *
2**p. ilogb and ilogbf examine the argument
val, and return p. The functions frexp and
frexpf are similar to ilogb and ilogbf, but also
return m.
Returns
ilogb and ilogbf return the power of two used to form the
floating-point argument.
If val is 0, they return FP_ILOGB0.
If val is infinite, they return INT_MAX.
If val is NaN, they return FP_ILOGBNAN.
(FP_ILOGB0 and FP_ILOGBNAN are defined in math.h, but in turn are
defined as INT_MIN or INT_MAX from limits.h. The value of FP_ILOGB0 may be
either INT_MIN or -INT_MAX. The value of FP_ILOGBNAN may be either INT_MAX or
INT_MIN.)
Portability
C99, POSIX