C++ function overload resolution - bool vs string

Question

I've found some unexpected behavior using the VC++2010 compiler with function overloading:

struct A {
  A();
  void O(const bool in);       //(1)
  void O(const std::string in);//(2)
}

Some of the following calls do not resolve like I would think:

A a;
a.O(true);//calls (1)
a.O("what?");//calls (1)
a.O(std::string("better..."));//calls (2)

Can someone explain to me why the second call resolves to the boolean function and what the motivation behind resolving in that way is?

This is really close since the exact same thing is happening: http://stackoverflow.com/questions/24411134/empty-string-is-interpreted-as-bool-in-constructor — chris, Jun 26 '14 at 20:40

bstamour · Answer 1 · 2014-06-26T20:53:03.340

2

The type of "what?" is char const[6], which after decaying to char const* while being passed into the function, is implicitly convertible to bool. The standard conversion takes precedence over user-defined implicit conversions, like the case of converting char const* to std::string.

edited Jun 26 '14 at 20:53

answered Jun 26 '14 at 20:41

bstamour

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C++ function overload resolution - bool vs string

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