Question

I’m hunting a bug in code and I have a problem:

 class a
 {
 public:
 void foo(int a) {}
 }

  std::set<a*> set;
  std::set<a*>::iterator it = set.begin();

  it->foo(55); //gives me error:
  // error: request for member ‘foo’ in ‘* it.std::_Rb_tree_const_iterator<_Tp>::operator-><a*>()’, which is of pointer type ‘a* const’ (maybe you meant to use ‘->’ ?)

Why it doesn’t allow me to use non-const function on it? What can I do to have a set of non-const pointers without using casting?

Answer 1

You need to dereference twice:

(*it)->foo(55);

– it is an iterator to a pointer. Your code would be correct if you had an std::set<a> instead of an std::set<a*>.