nan, nanf, nanl
From cppreference.com
| Defined in header <math.h>
|
||
| float nanf( const char* arg ); |
(since C99) | |
| double nan( const char* arg ); |
(since C99) | |
| long double nanl( const char* arg ); |
(since C99) | |
Converts the implementation-defined character string arg into the corresponding quiet NaN value, as if by calling strtof, strtod, or strtold, respectively, as follows:
The call nan("n-char-sequence"), where n-char-sequence is a sequence of digits, Latin letters, and underscores, is equivalent to the call strtod("NAN(n-char-sequence)", (char**)NULL);.
The call nan("") is equivalent to the call strtod("NAN()", (char**)NULL);.
The call nan("string"), where string is neither an n-char-sequence nor an empty string, is equivalent to the call strtod("NAN", (char**)NULL);.
Parameters
| arg | - | narrow character string identifying the contents of a NaN |
Return value
The quiet NaN value that corresponds to the identifying string arg or zero if the implementation does not support quiet NaNs.
Example
Run this code
#include <stdio.h> #include <math.h> #include <stdint.h> #include <inttypes.h> #include <string.h> int main(void) { double f1 = nan("1"); uint64_t f1n; memcpy(&f1n, &f1, sizeof f1); printf("nan(\"1\") =%f (%" PRIx64 ")\n", f1, f1n); double f2 = nan("2"); uint64_t f2n; memcpy(&f2n, &f2, sizeof f2); printf("nan(\"2\") =%f (%" PRIx64 ")\n", f2, f2n); double f3 = nan("0xF"); uint64_t f3n; memcpy(&f3n, &f3, sizeof f3); printf("nan(\"0xF\") =%f (%" PRIx64 ")\n", f3, f3n); }
Possible output:
nan("1") = nan (7ff8000000000001)
nan("2") = nan (7ff8000000000002)
nan("0xF") = nan (7ff800000000000f)See also
| (C99) |
checks if the given number is NaN (function) |
| (C99) |
evaluates to a quiet NaN of type float (macro constant) |