如何在C++中初始化靜態類對象？

Question

Lane.h

class Lane{ 
    //other declarations.. 
public: 
    Lane(){} 
    static Lane left_line; 
    static Lane right_line; 
}; 

Lane.cpp

Lane Lane::left_line; 

的main.cpp

int main(){ 
    Lane::left_line(); //doesn't work 

我在做什麼錯還是我做的一切錯誤。我實際上對靜態對象如何正確工作感到困惑。

Answer 1

static成員在類中聲明並在類之外初始化一次。沒有必要再次調用構造函數。我已經在Lane課程中添加了一種方法，使其更清晰。

class Lane{ 
    //other declarations.. 
public: 
    Lane(){} 
    static Lane left_line; //<declaration 
    static Lane right_line; 

    void use() {}; 
}; 

Lane.cpp

Lane Lane::left_line; //< initialisation, calls the default constructor of Lane 

的main.cpp

int main() { 
    // Lane::left_line(); //< would try to call a static function called left_line which does not exist 
    Lane::left_line.use(); //< just use it, it was already initialised 
} 

您可以更加明顯的做這做初始化：

Lane Lane::left_line = Lane(); 

Lane.cpp。