显式初始化没有默认构造函数的成员 [英] Explicitly initialize member which does not have a default constructor

问题描述

我试图实例化一个没有默认构造函数的对象，因此可以从类中的任何方法引用它。我在我的头文件中声明它，但编译器说，创建它的类的构造函数必须显式初始化成员，我不能弄清楚如何做。

I´m trying to instantiate an object which has no default constructor so it can be referenced from any methods inside the class. I declared it in my header file, but the compiler says that the constructor for the class creating it must explicitly initialize the member, and I can´t figure out how to do that.

非常感谢您的回答，提前谢谢！

Really appreciate your answers, thank you in advance!

MyClass.h

MyClass.h

include "MyOtherClass.h"

class myClass {

    private:
        MyOtherClass myObject;

    public:
        MyClass();
        ~MyClass();
        void myMethod();

}

MyClass.cpp

MyClass.cpp

include "MyClass.h"

MyClass::MyClass() {

   MyOtherClass myObject (60);
   myObject.doSomething();

}

MyClass::myMethod() {

    myObject.doSomething();

}

MyOtherClass.h

MyOtherClass.h

class MyOtherClass {

   private:
      int aNumber;

   public:
      MyOtherClass (int someNumber);
      ~MyOtherClass();
      void doSomething();
}

MyOtherClass.cpp

MyOtherClass.cpp

include "MyOtherClass.h"

MyOtherClass::MyOtherClass (int someNumber) {
   aNumber = someNumber;
}

void MyOtherClass::doSomething () {
    std::cout << aNumber;
}

推荐答案

当你在c ++中创建一个对象，默认情况下，它运行所有的对象的默认构造函数。你可以通过这个来告诉要使用的构造函数的语言：

You are almost there. When you create a object in c++, by default it runs the default constructor on all of it's objects. You can tell the language which constructor to use by this:

MyClass::MyClass() : myObject(60){

   myObject.doSomething();

}

这样就不会试图找到默认构造函数并呼叫您想要哪一个。

That way it doesn't try to find the default constructor and calls which one you want.

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