ilogbf3
Get integer exponent of a floating-point value
Part of ilogb(3).
Usage
#include <math.h>
int ilogb(double x); int ilogbf(float x); int ilogbl(long double x);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
ilogb():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| _XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
ilogbf(), ilogbl():
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
Library
Math library (libm, -lm)
Overview
These functions return the exponent part of their argument as a signed integer. When no error occurs, these functions are equivalent to the corresponding logb(3) functions, cast to int.
Return value
On success, these functions return the exponent of x, as a signed integer.
If x is zero, then a domain error occurs, and the functions return FP_ILOGB0.
If x is a NaN, then a domain error occurs, and the functions return FP_ILOGBNAN.
If x is negative infinity or positive infinity, then a domain error occurs, and the functions return INT_MAX.
Errors
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
- Domain error: x is 0 or a NaN
-
An invalid floating-point exception (
FE_INVALID) is raised, and errno is set to EDOM (but see BUGS).
- Domain error: x is an infinity
-
An invalid floating-point exception (
FE_INVALID) is raised, and errno is set to EDOM (but see BUGS).
Attributes
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| ilogb(), ilogbf(), ilogbl() | Thread safety | MT-Safe |
Releases
12 releases since Debian 3.1 (Sarge); the text changed 11 times.