Embedded statements are not allowed in constant expressions, such as the value of an enumeration constant, the width of a bit-field, or the initial value of a static variable.
在常量表达式，比如枚举型常量、位域的宽度或是静态变量的初始值，是不允许使用在这种声明中的。
It is needed when there should be a specific list of constant values to be used for the simple type defined by the enumeration.
当枚举定义的简单类型使用常数的特殊列表时，就会需要这种类型了。
It is needed when there should be a specific list of constant values to be used for the simple type defined by the enumeration.
当枚举定义的简单类型使用常数的特殊列表时，就会需要这种类型了。
应用推荐