NAME

ilogb — return exponent as an integer value

SYNOPSIS

#include <math.h>

int
ilogb(double x);

int
ilogbl(long double x);

int
ilogbf(float x);

The ilogb() functions return the exponent of x as a signed integer value.

ilogb(±0) returns FP_ILOGB0.

ilogb(±infinity) returns INT_MAX.

ilogb(x) returns FP_ILOGBNAN if x is a NaN.

A range error may occur if x is 0, ±infinity, or a nan.

The special return values FP_ILOGB0 and FP_ILOGBNAN are defined in math.h, and may differ between platforms. INT_MAX is defined in limits.h.

The ilogb() functions conform to ISO/IEC 9899:2011.