CODEWITHSUNDEEP
c++classconstructor
kirill_igum
kirill_igum

Reputation: 3993

initiate class with an argument in class declaration

in my object State, i'd like to have object pq. but pq needs to be initialized with a parameter. is there a way to include a class that depends on a parameter into another class?

file.h

class Pq
{
  int a;
  Pq(ClassB b);
};
class State
{
  ClassB b2;
  Pq pq(b2);
  State(ClassB b3);
};

file.cc

State::State(ClassB b3) : b2(b3) {}

Upvotes: 0

Views: 126

Answers (2)

Arunmu
Arunmu

Reputation: 6901

Class State{
public:
       State(ClassB& bref):b2(bref),pq(b2){} // Depends on the order you declare objects
                                             // in private/public/protected

private:
    ClassB b2;
    Pq pq;

};

In the above code you have to maintain that order in the initialization list otherwise you will get what not expected..therefore quite risky

Upvotes: 1

Arvid
Arvid

Reputation: 11245

You can initialize it in the initializer list, just like you do with b2:

State::State(ClassB b3) : b2(b3), pq(b2) {}

Keep in mind that members are initialized in the order they are declared in the header file, not the order of the initializers in the initializer list.

You need to remove the attempt at initialize it in the header as well:

class Pq
{
  int a;
  Pq(ClassB b);
};
class State
{
  ClassB b2;
  Pq pq;
  State(ClassB b3);
};

Upvotes: 2

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