c/numeric/math/nan

Converts the implementation-defined character string into the corresponding quiet NaN value, as if by calling the appropriate parsing function, as follows:
 * The call, where is a sequence of digits, Latin letters, and underscores, is equivalent to the call.
 * The call is equivalent to the call.
 * The call, where is neither an  nor an empty string, is equivalent to the call.

@1@ The parsing function is strtof. @2@ The parsing function is strtod. @3@ The parsing function is strtold. @4@ The parsing function is strtod32. @5@ The parsing function is strtod64. @6@ The parsing function is strtod128.

Return value
The quiet NaN value that corresponds to the identifying string 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.

Error handling
This function is not subject to any of the error conditions specified in.