如何修改静态成员函数中的变量? [英] How can i modify variables in static member function?

问题描述

我在下面有一个代码，我想在静态函数中修改类的变量，但是有一些错误.我该如何使用"this"指针对其进行修复?

I have a code below, i want to modify class's variables in static function but there is some error. How can i fix it with "this" pointer?

对于类中的静态成员，无法访问"this"指针，另一方面，我正在尝试对Static成员函数中的类变量进行访问，因此，我正在寻找一种使用"this"指针的方法属于我"类的人.

There is no access to "this" pointer for static members in class,on the other hand I am trying to make an access to class variables in Static member function, therefore i am looking for a way to use "this" pointer of class "me" to do it.

class me {
  public:
     void X() { x = 1;}
     void Y() { y = 2;}

static void Z() {
  x = 5 ; y = 10;
}

public:
  int x, y;
};

int main() {
  me M;

  M.X();
  M.Y();
  M.Z();

  return 0;
}

我遇到了这个错误:

在静态成员函数中无效地使用了成员"me :: x".

invalid use of member ‘me::x’ in static member function.

推荐答案

您可以将指向实例的指针传递给该方法:

You can pass a pointer to an instance to the method:

class me {
public:
    void X() { x = 1;}
    void Y() { y = 2;}

    static void Z(me* this_) { // fake "this" pointer
      this_->x = 5 ;
      this_->y = 10;
    }

public:
    int x, y;
};


int main() {
    me M;

    M.X();
    M.Y();
    M.Z(&M);  // this works, but
    // usually you call static methods like this
    // me::Z(&M);

    return 0;
}

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