Constant

本节对C++中constant进行总结。

C++中的constant

本节总结C++中的constant:

	explanation	章节
const	cppreference cv (const and volatile) type qualifiers: type qualifier, defines that the type is constant.	C++\Language-reference\Basic-concept\Type-system\Type-system\Type-qualifier
enumerator	cppreference Enumeration declaration: An enumeration may include several explicitly named constants ("enumerators").	C++\Language-reference\Enum
constant expression	cppreference Constant expressions	C++\Language-reference\Expressions\Constant-expressions

Value category of constant

这个问题，还比较复杂，后续进行补充。

Constant initialization

另外，一个与constant有关的是Constant initialization。

TODO Constant and literal

literal type和constant之间的关系。

TODO enum VS const VS constexpr

参考

https://isocpp.org/blog/2016/05/quick-q-static-constexpr-int-vs-old-fashioned-enum-when-and-why

https://stackoverflow.com/questions/22867654/enum-vs-constexpr-for-actual-static-constants-inside-classes

https://stackoverflow.com/questions/2636303/how-to-initialize-a-private-static-const-map-in-c

enum VS constexpr

enum、constexpr都可以用于in-class static constant

Application

主要用于compile time，参见C-and-C++\Compile-time-and-run-time，其中非常重要的一点是：static polymorphism。

TODO

c++ 11 initialize a dict constexpr

https://stackoverflow.com/questions/28530278/undefined-reference-to-static-constexpr-char

https://devblogs.microsoft.com/cppblog/constexpr-and-aggregate-initialization/