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# nan, nanf, nanl

From cppreference.com
< c‎ | numeric‎ | math

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. The call std::nan("string") is equivalent to the call std::strtod("NAN(string)", (char**)NULL);.

### [edit] Parameters

arg | - | narrow character string identifying the contents of a NaN, or an empty string

### [edit] Return value

The NaN value that corresponds to the identifying string `arg` or zero if the implemntation does not support quiet NaNs.

### [edit] See also

isnan (C99) | checks if the given number is NaN (function) [edit]
C++ documentation for nanf, nan, nand

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