if a member function does not operate member variable, should I always declare it static
如果成员函数不操作成员变量，我应该始终声明它是静态的吗？
In general, it’s not necessary to declare a member function as static if it doesn’t operate on member variables. However, there are some cases where it can be useful to declare a member function as static.
一般来说，如果成员函数不对成员变量进行操作，则没有必要将其声明为静态。但是，在某些情况下，将成员函数声明为静态可能很有用。
One reason to declare a member function as static is if it doesn’t need to access any member variables or non-static member functions. In this case, declaring the function as static can make it clearer to readers of the code that the function doesn’t rely on any specific object state.
将成员函数声明为静态的一个原因是它不需要访问任何成员变量或非静态成员函数。在这种情况下，将函数声明为静态可以让代码的读者更清楚地知道函数不依赖于任何特定的对象状态。
Another reason to declare a member function as static is if you want to use it to define a default value for a member variable that is itself static. In this case, the static member function can be used to initialize the static member variable.
将成员函数声明为静态的另一个原因是，如果您想使用它来为本身是静态的成员变量定义默认值。在这种情况下，静态成员函数可用于初始化静态成员变量。
Overall, whether to declare a member function as static or not depends on the specific circumstances and the needs of your code. It’s not always necessary, but it can be useful in some situations.
总体而言，是否将成员函数声明为静态取决于特定情况和代码的需要。这并不总是必要的，但在某些情况下可能很有用。