cpp/types/numeric limits/quiet NaN

Returns the special value "quiet not-a-number", as represented by the floating-point type. Only meaningful if. In IEEE 754, the most common binary representation of floating-point numbers, any value with all bits of the exponent set and at least one bit of the fraction set represents a NaN. It is implementation-defined which values of the fraction represent quiet or signaling NaNs, and whether the sign bit is meaningful.