An operation of the form op x or x op, where op is an overloadable unary
operator, and x is an expression of
type X, is processed as follows:
?The set of candidate user-defined operators provided by X for the
operation operator op(x) is
determined using the rules of ?4.2.5.
?If the set of candidate user-defined operators is not empty, then this
becomes the set of candidate
operators for the operation. Otherwise, the predefined unary operator op
implementations become the
set of candidate operators for the operation. The predefined
implementations of a given operator are
specified in the description of the operator (?4.5 and ?4.6).
?The overload resolution rules of ?4.4.2 are applied to the set of
candidate operators to select the best
operator with respect to the argument list (x), and this operator becomes
the result of the overload
resolution process. If overload resolution fails to select a single best
operator, a compile-time error
occurs.
operator, and x is an expression of
type X, is processed as follows:
?The set of candidate user-defined operators provided by X for the
operation operator op(x) is
determined using the rules of ?4.2.5.
?If the set of candidate user-defined operators is not empty, then this
becomes the set of candidate
operators for the operation. Otherwise, the predefined unary operator op
implementations become the
set of candidate operators for the operation. The predefined
implementations of a given operator are
specified in the description of the operator (?4.5 and ?4.6).
?The overload resolution rules of ?4.4.2 are applied to the set of
candidate operators to select the best
operator with respect to the argument list (x), and this operator becomes
the result of the overload
resolution process. If overload resolution fails to select a single best
operator, a compile-time error
occurs.
博客介绍了形如op x或x op的操作处理方式,其中op是可重载一元运算符,x是类型X的表达式。先确定X提供的候选用户定义运算符集合,若为空则使用预定义运算符实现,最后应用重载解析规则选择最佳运算符,若失败则编译报错。
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