Using declaration in C++

Question

namespace A {
  void F() {}
  namespace B {
    void F(int) {}  
  }
}

using A::B::F;

namespace A {
  void G() {
    F();   // OK
    F(1);  // Error: too many arguments to function void A::F()
  }
}

int main() { return 0; }

I have this piece of code.

I defined two functions with same names but different signatures.

Then I use a using-declaration using A::B::F.

In A::G() compiler tries to resolve A::F() before A::B::F().

Are there any orders if there are such conflicts?

Brian Bi · Accepted Answer · 2015-04-21 17:14:16Z

4

The deepest nested scope is searched first, and scopes are then searched outward if the name is not found. So first it would find a block-scope declaration of F inside G, if any; then it would find a declaration at the namespace scope of A, if any; and if that too failed it would search the global scope. Since using A::B::F; appears at global scope, A::F is always found first. Perhaps you should move the using declaration inside A.

answered Apr 21, 2015 at 17:14

Brian Bi

123k13 gold badges197 silver badges353 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

davepmiller · Accepted Answer · 2015-04-21 17:14:24Z

0

It's definitely about placement.

namespace A {
  void G() {


    F();   // OK, A::F

    using B::F;
    F(1);  // OK, A::B::F
  }
}

answered Apr 21, 2015 at 17:14

davepmiller

2,7353 gold badges37 silver badges65 bronze badges

Collectives™ on Stack Overflow

Using declaration in C++

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related