std::nan, std::nanf, std::nanl - cppreference.com (original) (raw)
| Defined in header | ||
|---|---|---|
| float nanf( const char* arg ); | (1) | (since C++11) |
| double nan ( const char* arg ); | (2) | (since C++11) |
| long double nanl( const char* arg ); | (3) | (since C++11) |
Converts the character string arg into the corresponding quiet NaN value, as if by calling std::strtof, std::strtod, or std::strtold, respectively.
- The call std::nanf("n-char-sequence"), where n-char-sequence is a sequence of digits, ASCII letters, and underscores, is equivalent to the call std::strtof("NAN(n-char-sequence)", (char**)nullptr);.
The call std::nanf("") is equivalent to the call std::strtof("NAN()", (char**)nullptr);.
The call std::nanf("string"), where string is neither an n-char-sequence nor an empty string, is equivalent to the call std::strtof("NAN", (char**)nullptr);.
[edit] Parameters
| arg | - | narrow character string identifying the contents of a NaN |
|---|
[edit] Return value
The quiet NaN value that corresponds to the identifying string arg or zero if the implementation does not support quiet NaNs.
If the implementation supports IEEE floating-point arithmetic (IEC 60559), it also supports quiet NaNs.
[edit] Error handling
This function is not subject to any of the error conditions specified in math_errhandling.
[edit] Example
Possible output:
nan("1") = nan (7ff0000000000001) nan("2") = nan (7ff0000000000002)
[edit] See also
| isnan(C++11) | checks if the given number is NaN (function) [edit] |
|---|---|
| NAN(C++11) | evaluates to a quiet NaN of type float (macro constant) [edit] |
| has_quiet_NaN[static] | identifies floating-point types that can represent the special value "quiet not-a-number" (NaN) (public static member constant of std::numeric_limits) [edit] |
| has_signaling_NaN[static] | identifies floating-point types that can represent the special value "signaling not-a-number" (NaN) (public static member constant of std::numeric_limits) [edit] |
| quiet_NaN[static] | returns a quiet NaN value of the given floating-point type (public static member function of std::numeric_limits) [edit] |
| signaling_NaN[static] | returns a signaling NaN value of the given floating-point type (public static member function of std::numeric_limits) [edit] |
| C documentation for nanf, nan, nanl |