什么是枚举变量的缺省值 [英] what is the default value for enum variable
问题描述
这是枚举变量,任何人都知道,如果它总是默认为第一个元素?
An enum variable, anyone know if it is always defaulting to the first element?
推荐答案
这是什么枚举重$ P $成员psents值 0
。具体而言,从文档:
It is whatever member of the enumeration represents the value 0
. Specifically, from the documentation:
在枚举è
的默认值为由前pression产生的值(E)0
。
作为一个例子,采取以下枚举:
As an example, take the following enum:
enum E
{
Foo, Bar, Baz, Quux
}
在不覆盖缺省值,打印默认(E)
返回富
,因为它是第一个存在的元素。
Without overriding the default values, printing default(E)
returns Foo
since it's the first-occurring element.
然而,这是的不一定的一个枚举的 0
被重新$ P的第一个成员psented $。例如,如果你这样做:
However, it is not always the case that 0
of an enum is represented by the first member. For example, if you do this:
enum F
{
// Give each element a custom value
Foo = 1, Bar = 2, Baz = 3, Quux = 0
}
印刷默认(F)
会给你 QUUX
,不是富
。
如果没有任何元素的枚举 0
:
If none of the elements in an enum G
correspond to 0
:
enum G
{
Foo = 1, Bar = 2, Baz = 3, Quux = 4
}
默认(G)
返回字面上 0
,虽然它的类型仍然是
default(G)
returns literally 0
, although its type remains as G
(as quoted by the docs above, a cast to the given enum type).
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