C++如何訪問私有成員在類的std :: for_each的內部

Question

所以，我有我的課：

class base 
{ 
public: 
    base (int member) : m_member(member) {}; 
    ~base() {}; 

    void func(void) 
    { 
    std::for_each(something.begin(), something.end(), [](OtherClass& myOtherClass) 
    { 
     GLfloat* stuff = myOtherClass.GetStuff(); 
     m_member = 1; //How can I access the private member here? 
    }); 
    }; 
private: 
    int m_member; 
} 

我得到這樣的警告：

'm_member' requires the compiler to capture 'this' but the current default capture mode does not allow it 

而這個錯誤：

'm_member' undeclared identifier 

如何訪問foreach中的私有成員m_member？

Answer 1

在lambda之前的括號中，您可以捕獲函數體所需的符號。在這種情況下，你需要捕獲this，因爲你使用它的成員：

[this](OtherClass& myOtherClass) 
    { 
     GLfloat* stuff = myOtherClass.GetStuff(); 
     m_member = 1; 
    }); 

又見cpp reference約lambda表達式：

capture-list - comma-separated list of zero or more captures, optionally beginning with a capture-default. Capture list can be passed as follows (see below for the detailed description):

[a,&b] where a is captured by value and b is captured by reference.

[this] captures the this pointer by value

[&] captures all automatic variables odr-used in the body of the lambda by reference

[=] captures all automatic variables odr-used in the body of the lambda by value

[] captures nothing