cpp/numeric/math/trunc

@1-3@ Computes the nearest integer not greater in magnitude than. @A@ Additional overloads are provided for all integer types, which are treated as.

Return value
If no errors occur, the nearest integer value not greater in magnitude than (in other words,  rounded towards zero) is returned.

Error handling
Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559),
 * The current rounding mode has no effect.
 * If is ±∞, it is returned, unmodified
 * If is ±0, it is returned, unmodified
 * If is NaN, NaN is returned