Created on 2006-05-28.00:00:00 last changed 172 months ago
Proposed resolution:
Change the Returns: clause in 3.2.2.4 to:
Returns: Returns the result of the conversion of
*this
to the typelong long
, as if performed by the expressionllroundd32(*this)
while the decimal rounding direction mode [3.5.2]FE_DEC_TOWARD_ZERO
is in effect.
Change the Returns: clause in 3.2.3.4 to:
Returns: Returns the result of the conversion of
*this
to the typelong long
, as if performed by the expressionllroundd64(*this)
while the decimal rounding direction mode [3.5.2]FE_DEC_TOWARD_ZERO
is in effect.
Change the Returns: clause in 3.2.4.4 to:
Returns: Returns the result of the conversion of
*this
to the typelong long
, as if performed by the expressionllroundd64(*this)
llroundd128(*this)
while the decimal rounding direction mode [3.5.2]FE_DEC_TOWARD_ZERO
is in effect.
In a private email, Daniel writes:
I would like to ask, what where the reason for the decision to define the semantics of the integral conversion of the decimal types, namely
"operator long long() const; Returns: Returns the result of the conversion of *this to the type long long, as if performed by the expression llrounddXX(*this)."where XX stands for either 32, 64, or 128, corresponding to the proper decimal type. The exact meaning of llrounddXX is not given in that paper, so I compared it to the corresponding definition given in C99, 2nd edition (ISO 9899), which says in 7.12.9.7 p. 2:
"The lround and llround functions round their argument to the nearest integer value, rounding halfway cases away from zero, regardless of the current rounding direction. [..]"
Now considering the fact that integral conversion of the usual floating-point types ("4.9 Floating-integral conversions") has truncation semantic I wonder why this conversion behaviour has not been transferred for the decimal types.
Robert comments:
Also, there is a further error in the Returns: clause for converting decimal::decimal128
to long long
. It currently calls llroundd64
, not llroundd128
.
History | |||
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Date | User | Action | Args |
2010-10-21 18:28:33 | admin | set | messages: + msg3181 |
2006-05-28 00:00:00 | admin | create |