c ++ - constructeur par défaut pour une classe avec un membre de données de référence ? -Débordement de pile

I have a class which I create an array/vector of, so I require a default constructor. However, this class has a data member which is a reference. The reference needs to be initialized in the constructor and I cannot do this in a default constructor because I cannot.

How should I solve this?

class MyClass{
public:
    MyClass(); //Cannot instantiate s??
    MyClass(Something& s);
    Something& s;
}

MyClass array[10];   //MyClass needs a default constructor but a default 
                     //constructor wont be able to initialize s

A class with a reference member needs to set the reference in its constructors. In most cases this means, that the class cannot have a default constructor. The best way to solve the problem is use a pointer instead of a reference:

class MyClass{
public:
    MyClass() : s_(0) {}
    MyClass(Something* s) : s_(s) {}
    Something* s_;
}

As I commented above, by the description alone, I would say that it's a classical case where s should be a Something* rather than a Something&...

OTOH, this work perfectly, so you don't need a default constructor if you just initialize each element of your array:

struct Something { };

struct MyClass {
  MyClass(Something& ss) : s{ss} {}
  Something& s;
};

int main() {
  Something a, b, c, d;
  Something v[10] = { a, b, c, d, a, b, c, d, a, b };
  return 0;
}

You got two options here. First - and better - change Something& s; to Something* s; and initialize it inside the contructor like this:

MyClass(){this->s = 0;};
MyClass(Something& s){this->s = *s;};

And second - worse - create a special container for Something:

struct somethingContainer{
    Something &s;
    somethingContainer(Something &s): s(s){};
};

class MyClass{
   somethingContainer *container;
};

In that case - you have to allocate the memory manually with new, and clean it with delete.

I have a class which I create an array/vector of, so I require a default constructor. However, this class has a data member which is a reference. The reference needs to be initialized in the constructor and I cannot do this in a default constructor because I cannot.

How should I solve this?

class MyClass{
public:
    MyClass(); //Cannot instantiate s??
    MyClass(Something& s);
    Something& s;
}

MyClass array[10];   //MyClass needs a default constructor but a default 
                     //constructor wont be able to initialize s

A class with a reference member needs to set the reference in its constructors. In most cases this means, that the class cannot have a default constructor. The best way to solve the problem is use a pointer instead of a reference:

class MyClass{
public:
    MyClass() : s_(0) {}
    MyClass(Something* s) : s_(s) {}
    Something* s_;
}

As I commented above, by the description alone, I would say that it's a classical case where s should be a Something* rather than a Something&...

OTOH, this work perfectly, so you don't need a default constructor if you just initialize each element of your array:

struct Something { };

struct MyClass {
  MyClass(Something& ss) : s{ss} {}
  Something& s;
};

int main() {
  Something a, b, c, d;
  Something v[10] = { a, b, c, d, a, b, c, d, a, b };
  return 0;
}

You got two options here. First - and better - change Something& s; to Something* s; and initialize it inside the contructor like this:

MyClass(){this->s = 0;};
MyClass(Something& s){this->s = *s;};

And second - worse - create a special container for Something:

struct somethingContainer{
    Something &s;
    somethingContainer(Something &s): s(s){};
};

class MyClass{
   somethingContainer *container;
};

In that case - you have to allocate the memory manually with new, and clean it with delete.

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