''的构造函数必须显式初始化引用成员“ [英] Constructor for '' must explicitly initialize the reference member ''

问题描述

我有这个类

  class CamFeed {
 public：
 // constructor 
 CamFeed（ofVideoGrabber& cam）; 
 ofVideoGrabber& cam; 
 
}; 
  

这个构造函数：

  CamFeed :: CamFeed（ofVideoGrabber& cam）{
 this-> cam = cam; 
} 
  

我在构造函数中遇到此错误：
构造函数

你需要使用构造函数初始化器列表：

 解决方案 ：CamFeed（ofVideoGrabber& cam）：cam（cam）{} 
  

这是因为引用必须引用因此不能默认构造。一旦你在构造函数体中，所有的数据成员都被初始化了。你的 this-> cam = cam; 行真的是一个赋值，赋值 cam 无论 this-> cam 是指。

I have this class

class CamFeed {
public:
    // constructor
    CamFeed(ofVideoGrabber &cam); 
    ofVideoGrabber &cam;

};

And this constructor:

CamFeed::CamFeed(ofVideoGrabber &cam) {
    this->cam = cam;
}

I get this error on the constructor: Constructor for '' must explicitly initialize the reference member ''

What is a good way to get around this?

解决方案

You need to use the constructor initializer list:

CamFeed::CamFeed(ofVideoGrabber& cam) : cam(cam) {}

This is because references must refer to something and therefore cannot be default constructed. Once you are in the constructor body, all your data members have been initialized. Your this->cam = cam; line would really be an assignment, assigning the value referred to by cam to whatever this->cam refers to.

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