CODEWITHSUNDEEP
c++copy-constructor
helpermethod
helpermethod

Reputation: 62185

C++ Is the copy constructor called here?

Suppose you have a functions like this:

Foo foo() {
  Foo foo;

  // more lines of code

  return foo; // is the copy constructor called here?
}

Foo bar() {
  // more lines of code

  return Foo(); // is the copy constructor called here?
}

int main() {
  Foo a = foo();
  Foo b = bar();  
}

When any of the functions return, is the copy constructor called (suppose there would be one)?

Upvotes: 5

Views: 228

Answers (3)

xtofl
xtofl

Reputation: 41509

It may be called. It also may be optimized away. See some other question in the same direction.

Upvotes: 2

aschepler
aschepler

Reputation: 72356

It might be called, or it might not be called. The compiler has the option of using the Return Value Optimization in both cases (though the optimization is a bit easier in bar than in foo).

Even if RVO eliminates the actual calls to the copy constructor, the copy constructor must still be defined and accessible.

Upvotes: 10

Nikolai Fetissov
Nikolai Fetissov

Reputation: 84169

Depends on the Return Value Optimization being applied or not.

Upvotes: 8

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