ilogb, ilogbf—get exponent of floating-point number #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 -
INT_MAX (INT_MAX is defined in limits.h). If val is
infinite, or NaN, they return INT_MAX.
Portability
Neither ilogb nor ilogbf is required by ANSI C or by
the System V Interface Definition (Issue 2).