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      1. 在 C++ 中定义静态成员

        时间:2023-12-03
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                  本文介绍了在 C++ 中定义静态成员的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着跟版网的小编来一起学习吧!

                  问题描述

                  我正在尝试像这样定义一个公共静态变量:

                  I am trying to define a public static variable like this :

                  public :
                           static int j=0;        //or any other value too
                  

                  我在这一行遇到编译错误:ISO C++ 禁止非常量静态成员 `j' 的类内初始化.

                  I am getting a compilation error on this very line : ISO C++ forbids in-class initialization of non-const static member `j'.

                  1. 为什么在 C++ 中不允许?

                  1. Why is it not allowed in C++ ?

                  为什么允许初始化 const 成员?

                  Why are const members allowed to be initialized ?

                  这是否意味着 C++ 中的静态变量不像 C 中那样用 0 初始化?

                  Does this mean static variables in C++ are not initialized with 0 as in C?

                  谢谢!

                  推荐答案

                  (1.) 为什么在 C++ 中不允许?

                  (1.) Why is it not allowed in C++ ?

                  来自 Bjarne Stroustrup 的 C++ 风格和技术常见问题解答:

                  类通常在头文件中声明,而头文件通常包含在许多翻译单元中.但是,为了避免复杂的链接器规则,C++ 要求每个对象都有唯一的定义.如果 C++ 允许在类中定义需要作为对象存储在内存中的实体,那么这条规则就会被打破.

                  A class is typically declared in a header file and a header file is typically included into many translation units. However, to avoid complicated linker rules, C++ requires that every object has a unique definition. That rule would be broken if C++ allowed in-class definition of entities that needed to be stored in memory as objects.

                  (2.) 为什么允许 const 成员被初始化?

                  (2.) Why are const members allowed to be initialized ?

                  [直接说得更好]

                  (3.) 这是否意味着静态变量在 C++ 中没有用 0 初始化为在 C 中?

                  (3.) Does this mean static variables in C++ are not initialized with 0 as in C?

                  据我所知,只要您在 .cpp 中声明静态成员 var,如果您不另外指定,它将被零初始化:

                  As far as I know, as long as you declare the static member var in a .cpp it will be zero-initialized if you don't specify otherwise:

                  // in some .cpp
                  int Test::j; // j = int();
                  

                  这篇关于在 C++ 中定义静态成员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跟版网!

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