cpp/numeric/math/nan

Converts the character string into the corresponding quiet NaN value, as if by calling std, std, or std, respectively.

@1@ The call, where is a sequence of digits, ASCII 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.

@2@ Same as, but calls std instead of std. @3@ Same as, but calls std instead of std.

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.