c++constructorconstantsctor-initializer

How to initialize a const field in constructor?

Imagine I have a C++ class Foo and a class Bar which has to be created with a constructor in which a Foo pointer is passed, and this pointer is meant to remain immutable in the Bar instance lifecycle. What is the correct way of doing it?

In fact, I thought I could write like the code below but it does not compile..

class Foo;

class Bar {
public:
    Foo * const foo;
    Bar(Foo* foo) {
        this->foo = foo;
    }
};

class Foo {
public:
  int a;
};

Any suggestion is welcome.

Solution

  • You need to do it in an initializer list:

    Bar(Foo* _foo) : foo(_foo) {
}

    (Note that I renamed the incoming variable to avoid confusion.)