CODEWITHSUNDEEP
c++constructorinitialization
user5624945
user5624945

Reputation: 37

How can I initialize with a constructor an object from another class?

I'm new at learning c++ and a have stuck in constructors.I have a class Teacher and a Class Subject. In class Teacher a have an object Subject S[]. How I can initialize with constructor from class Teacher the S[]? I have tried this: in Teacher.h file

class Teacher 
{
  private:
    string name;
    Subject *S[20];
  public:
    Teacher();
}

in Teacher.cpp file

Teacher::Teacher()
{
  name=" ";
  for(int i=0; i<20; i++)
  {
    S[i].Subject();
  }
}

in Subject.cpp file the Constructor is:

Subject::Subject()
{
  day=0;
  hour=0;
  for(int i=0; i<10; i++)
  {
    classroom[i]=" ";
  }
}

Upvotes: 0

Views: 91

Answers (2)

eerorika
eerorika

Reputation: 238461

In class Teacher a have an object Subject S[]

No you dont: 

Subject *S[20];

Teacher::S is an array of pointers.

S[i].Subject();

. is used for member access. Pointers do not have members, so this is syntactically wrong. Besides, you never call a constructor directly. It is called automatically as a consequence of initializing a variable, or a new expression.

It seems that to want to have an array of Subject objects as a member instead. This is how you would declare such member:

Subject S[20];

The objects in the array will be constructed before the body of Teacher constructor is executed.

Upvotes: 1

Bathsheba
Bathsheba

Reputation: 234875

The way you currently have it, you'd have to write

S[i] = new Subject();

rather than

S[i].Subject();

But that burdens you with having to remember to call delete at some point. It would be far better to use

std::list<Subject> S;

in place of

Subject *S[20];

and then push_back or even the flashier emplace_back in place of S[i].Subject();

See http://en.cppreference.com/w/cpp/container/list

Upvotes: 1

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