c# - 基于什么优先规则 a[x].SomeMember 被评估为 (a[x]).SomeMember 而不是……？

Question

a) 点运算符 ( a.x ) 和索引运算符 ( a[x] ) 具有相同的优先级。因此，根据什么优先规则，表达式 a[x].SomeMember 被评估为 (a[x]).SomeMember 而不是 (a.SomeMember ) [x]?

b) 转换运算符是一元运算符(因此优先级低于点运算符)，因此表达式 (int)a.x 被评估为 (int)(a.x) ?

谢谢

Answer 1

对于一个)

来自 C# 规范，第 7.2.1 节:

When an operand occurs between two operators with the same precedence, the associativity of the operators controls the order in which the operations are performed:

• Except for the assignment operators, all binary operators are left-associative, meaning that operations are performed from left to right. For example, x + y + z is evaluated as (x + y) + z.
• The assignment operators and the conditional operator (?:) are right-associative, meaning that operations are performed from right to left. For example, x = y = z is evaluated as x = (y = z).

这意味着在这种情况下，运算符将获得优先权，从左到右。

b) 是的，这是正确的。这是一个转换表达式，如 7​​.6.6 节所述，它应用于一元表达式，并且转换与一元运算符(7.6 节)一起分类并以相同的优先级处理。