问题描述
我们总是将纯虚函数声明为：
We always declare a pure virtual function as:
virtual void fun () = 0 ;
即，始终将其分配为0。
I.e., it is always assigned to 0.
我了解的是，这是将此函数的vtable条目初始化为NULL，此处的任何其他值都会导致编译时错误。
What I understand is that this is to initialize the vtable entry for this function to NULL and any other value here results in a compile time error. Is this understanding correct or not?
推荐答案
原因 = 0 是使用的原因是Bjarne Stroustrup认为在实现该功能时，他不能在C ++社区之外获得另一个关键字，例如 pure。这在他的书，第13.2.3节：
The reason =0 is used is that Bjarne Stroustrup didn't think he could get another keyword, such as "pure" past the C++ community at the time the feature was being implemented. This is described in his book, The Design & Evolution of C++, section 13.2.3:
他还明确指出不需要设置将vtable项设置为NULL，但这不是实现纯虚拟函数的最佳方法。
He also states explicitly that this need not set the vtable entry to NULL, and that doing so is not the best way of implementing pure virtual functions.
这篇关于为什么纯虚函数初始化为0？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！