c ++错误：在静态成员函数中无效使用成员“calls_object :: OBJECT” [英] c++ error: invalid use of member 'calls_object::OBJECT' in static member function

问题描述

我从下面的代码中得到了以下错误。

错误：无效的成员函数'calls_object :: OBJECT' |
错误：来自此位置

c $ c> OBJECT-> call（）; 第29行。

基本上，函数必须是静态的，因为它真的是简化版本代码
创建一个windows线程。我只是不能在静态函数中使用指针，但我可以创建静态函数中的对象没有问题。是否有其他方法？

  CreateThread（NULL，0，（LPTHREAD_START_ROUTINE）windowsthread，（LPVOID）i，NULL，&m_id ）; 
 
 static DWORD_PTR WINAPI windowsthread（）
 {
 OBJECT-> call（）; 
} 
  

l

 类对象
 {
 private：
 
 public：
 
 object（）{} 
〜 object（）{} 
 void call（）{} 
}; 
 class call_object 
 {
 private：
 
 object * OBJECT; 
 
 public：
 
 call_object（）
 {
 OBJECT = new object（）; 
} 
〜calls_object（）{} 
 
 #ifdef _WIN32 
 static void windows_function（）
 {
 OBJECT-& ）; 
} 
 #endif 
}; 
 int main（）
 {
 calls_object O; 
 
} 
  

解决方案

：

  static void windows_function（）
 {
 OBJECT-> call 
} 
  

声明为 static 。这意味着它不会收到一个隐式的这个指针：换句话说，它不会在 call_object的实例 。因此，它不能看到 OBJECT 成员变量。

将函数声明为非静态， code>作为 static 成员变量（在应用程序中更有意义）。

基本上，函数必须是静态的，因为它真的是创建一个windows线程的代码的简化版本

因为你（不幸的是）处理一个接受函数指针的函数（ CreateThread ），你甚至不能使用 std： ：bind 。然而， CreateThread 允许你提供一个接受一个指针的函数（ void ，见原型 ThreadProc ）。

只需传递指向对象的指针作为 CreateThread ，并让 windowsFunction（void *）接收该指针。在内部 windowsFunction（），它仍然是 static 或全局（实际上，你不需要 call_object class），你可以将该指针转换为指向 object 的指针，并调用 call c。

$ <$>

/ code>泄漏内存，因为您忘记了 delete 在 calls_object 中创建的指针构造函数：

 〜calls_object（）
 {
 delete object; //不要忘记！ 
} 
  

I got the following error from the code below.

error: invalid use of member 'calls_object::OBJECT' in static member function| error: from this location

from the line OBJECT->call(); line 29.

Basically the function must be static because its really a simplified version of the code which creates a windows thread. I just can't seem to use pointers within a static function but I can create the object within the static function no problem. Is there another way?

CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)windowsthread, (LPVOID)i, NULL, &m_id);

static DWORD_PTR WINAPI windowsthread()
{
    OBJECT->call();
}

l

class object
{
        private:

        public:

        object(){}
        ~object(){}
        void call(){}
};
class calls_object
{
    private:

        object* OBJECT;

    public:

    calls_object()
    {
        OBJECT = new object();
    }
    ~calls_object(){}

    #ifdef _WIN32
    static void windows_function()
    {
        OBJECT->call();
    }
    #endif
};
int main()
{
    calls_object O;

}

解决方案

This function:

static void windows_function()
{
    OBJECT->call();
}

Is declared as static. It means it does not receive an implicit this pointers: in other words, it does not operate on an instance of calls_object. Therefore, it cannot see the OBJECT member variable.

Either declare the function as non-static, or declare OBJECT as a static member variable (whatever makes more sense in your application).

Basically the function must be static because its really a simplified version of the code which creates a windows thread

Since you are (unfortunately) dealing with a function (CreateThread) that accepts a function pointer, you cannot even use std::bind. However, CreateThread lets you provide a function which accepts a pointer (to void, see the prototype of ThreadProc).

Just pass a pointer to an object as the fourth argument to CreateThread, and let windowsFunction(void*) receive that pointer. Inside windowsFunction(), which would still be static or global (in fact, you do not need the calls_object class at all), you can cast that pointer to a pointer to object and invoke call() on it.

---

Also notice, that your class calls_object is leaking memory, since you are forgetting to delete the pointer you created in calls_object's constructor:

~calls_object() 
{ 
    delete object; // DON'T FORGET THIS!
}

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