Manual Reference Pages - NANF (3)
- quiet NaNs
nan const char *s
nanf const char *s
nanl const char *s
macro expands to a quiet NaN (Not A Number).
Similarly, each of the
functions generate a quiet NaN value without raising an invalid exception.
should point to either an empty string or a hexadecimal representation
of a non-negative integer (e.g., "0x1234".)
In the latter case, the integer is encoded in some free bits in the
representation of the NaN, which sometimes store
machine-specific information about why a particular NaN was generated.
There are 22 such bits available for
variables, 51 bits for
variables, and at least 51 bits for a
.Vt long double .
is improperly formatted or represents an integer that is too large,
then the particular encoding of the quiet NaN that is returned
Calling these functions with a non-empty string isnt portable.
Another operating system may translate the string into a different
NaN encoding, and furthermore, the meaning of a given NaN encoding
varies across machine architectures.
If you understood the innards of a particular platform well enough to
know what string to use, then you would have no need for these functions
anyway, so dont use them.
functions and the
macro conform to
Visit the GSP FreeBSD Man Page Interface.
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