C++ 成员函数与自由函数

在编写程序时，很多时候我一直对这个设计决定感到困惑，但我不能 100% 确定何时应该使函数成为类的成员函数，何时离开它作为一个普通函数，当函数声明在头文件中公开时，其他源文件可以调用该函数.大多数情况下，对类成员变量的期望访问是否与决策有关?

解决方案

界面原理 by Herb Sutter

对于类 X，所有函数，包括自由函数，都
(a) 提及"X，和
(b) 随附" X
逻辑上是 X 的一部分，因为它们构成 X 接口的一部分.

有关深入讨论，请阅读 Herb Sutter 的命名空间和接口原则??.>

编辑
实际上，如果您想了解 C++，请阅读所有内容 Herb Sutter 写的内容:)

I keep on getting confused about this design decision a lot of the time when I'm writing programs, but I'm not 100% sure when I should make a function to be a member function of a class, when to leave it as a normal function in which other source files can call the function when the function declaration is exposed in a header file. Does the desired access to member variables of a class have to do with the decision most of the time?

解决方案

The Interface Principle by Herb Sutter

For a class X, all functions, including free functions, that both
(a) "mention" X, and
(b) are "supplied with" X
are logically part of X, because they form part of the interface of X.

For in depth discussion read Namespaces and the Interface Principle by Herb Sutter.

EDIT
Actually, if you want to understand C++ go and read everything what Herb Sutter has written :)