_BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L;
These functions return the smallest integral value that is not less than
is 1.0, and
These functions return the ceiling of
If x is integral, +0, -0, NaN, or infinite,
x itself is returned.
No errors occur.
POSIX.1-2001 documents a range error for overflows, but see NOTES.
The variant returning
also conforms to
SVr4, 4.3BSD, C89.
SUSv2 and POSIX.1-2001 contain text about overflow (which might set
or raise an
In practice, the result cannot overflow on any current machine,
so this error-handling stuff is just nonsense.
(More precisely, overflow can happen only when the maximum value
of the exponent is smaller than the number of mantissa bits.
For the IEEE-754 standard 32-bit and 64-bit floating-point numbers
the maximum value of the exponent is 128 (respectively, 1024),
and the number of mantissa bits is 24 (respectively, 53).)
The integral value returned by these functions may be too large
to store in an integer type
To avoid an overflow, which will produce undefined results,
an application should perform a range check on the returned value
before assigning it to an integer type.