cpp/numeric/math/nearbyint

@1-3@ Rounds the floating-point argument to an integer value in floating-point format, using the current rounding mode. @A@ Additional overloads are provided for all integer types, which are treated as.

Return value
The nearest integer value to, according to the current rounding mode, is returned.

Error handling
This function is not subject to any of the errors specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),
 * fe_inexact is never raised
 * If is ±∞, it is returned, unmodified
 * If is ±0, it is returned, unmodified
 * If is NaN, NaN is returned