n.说明符
The declarator must include an initializer. 声明者必须包含一个构造者。
In C++, when used with a string, extern specifies that the linkage conventions of another language are being used for the declarator(s). 变量或者函数可能被定义在另外一个源文件中，或者在同一个文件的后面部分。
direct abstract function declarator 直接抽象函数说明符
direct abstract array declarator 直接抽象阵列说明符
The "pointer to member" is distinct from the type "pionter", that is, a pointer to member is declared only by the pointer to member declarator syntax, and never by the pointer declarator syntax. 成员指针和普通指针截然不同。成员指针只能用成员指针声明的语法声明，不能用一般的指针声明方法声明。
adj.宣言的；公布的；申报的；陈述的
