班级成员是另一个班级的对象 [英] class member is another class' object

问题描述

我是C ++的新用户...

I am a new C++ user...

我有一个问题，关于如何声明作为另一个类"classB"的对象的类"classA"的成员，知道"classB"具有一个带有字符串参数的构造函数(除了默认构造函数外) ).我在网上做了一些有关此问题的研究，但是对解决我正在解决的问题并没有多大帮助.

I have a question regarding how to declare a member of a class "classA" that is an object of another class "classB", knowing that "classB" has a constructor that takes a string parameter (in addition to the default contructor). I did some research online about this issue however it did not help much to help me fix the issue I'm dealing with.

更具体地说，我想创建一个类，该类具有一个VideoCapture对象作为成员(VideoCapture是提供视频流的openCV类).

To be more specific, I want to create a class that has as member a VideoCapture object (VideoCapture is an openCV class that provide a video stream).

我的班级有这个原型:

class  myClass {
private:

string videoFileName ;

public:

myClass() ;

~myClass() ;

myClass (string videoFileName) ;
// this constructor will be used to initialize myCapture and does other
// things

VideoCapture myCapture (string videoFileName /* :  I am not sur what to put here */ )  ;

};

构造函数是:

myClass::myClass (string videoFileName){

VideoCapture myCapture(videoFileName) ;
// here I am trying to initialize myClass' member myCapture BUT
// the combination of this line and the line that declares this
// member in the class' prototype is redundant and causes errors...

// the constructor does other things here... that are ok...

}

我已尽最大努力以最简单的方式揭露我的问题，但我不确定自己是否能够做到...

I did my best to expose my issue in the simplest way, but I'm not sure I managed to...

感谢您的帮助和解答.

Thank you for your help and answers.

L.

推荐答案

您需要的是初始化列表:

What you need is initializer list:

myClass::myClass (string videoFileName) : myCapture(videoFileName) {
}

这将使用带有string参数的构造函数构造myCapture.

This will construct myCapture using its constructor that takes a string argument.

这篇关于班级成员是另一个班级的对象的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！