CODEWITHSUNDEEP
c++constructor
Sabien
Sabien

Reputation: 219

Does the constructor ignore portions of a member initialization list of an argument was supplied to the constructor?

I'm trying to understand fully how a constructor works in C++. Specifically, the member initialization list of a constructor.

Say you have a class Foobar with three data members bar, baz, and qux.

I set up my constructor like this:

Foobar(int bar, int baz, int qux)
    : bar(bar), baz(baz), qux(qux)
{
  // empty constructor body
}

My question is, does the member initialization list act as a "default"? Or does it ALWAYS happen? If, for example, the constructor was called with arguments, would the initialization list be ignored? I want to always have the qux data member be 0, unless otherwise specified. So would I instead write the member initialization line as:

  : nar(bar), bar(baz), qux(0)

Perhaps I'm totally misunderstanding the function of the member initialization list and maybe someone can set me straight.

Upvotes: 1

Views: 163

Answers (1)

Jon
Jon

Reputation: 437346

That constructor cannot be called without arguments, as all three of them are required. The compiler will remind you if you forget.

If you always want to initialize a member to a fixed value, the way to do that is exactly what you propose.

Upvotes: 1

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