abstract function class

基本解释

Classes derived from the abstract class must implement the pure virtual member function or they, too, are abstract classes.
由抽象類別衍生出來的類別必須實作純虛擬成員函式，否則它們也是抽象類別。
You open the file by calling the in function of the DL_Dxf object and passing a pointer to a class that inherits from the DL_CreationAdapter abstract class.
通過調用 DL_Dxf 對象的 in 函數竝將指針傳遞給一個繼承 DL_CreationAdapter 抽象類來打開此文件。
In a base class, abstract class is defined by declaring pure virtual function, a derived class must define all inherited pure virtual functions of its base classes to be concrete.
在基類中可以通過將虛函數聲明爲純虛函數的手段來定義抽象類，強制派生類在自己的類定義中實現虛函數的具躰功能。