Question

I’m attempting to solve the below exam question but I’m having difficulties with it.

Write a C++ function find_elem that takes two iterators first and last
of some sequence of elements of type T and an object obj of type T. It
returns the iterator to the first occurrence of obj in the range
(first, last), or the iterator last if obj is not in the sequence.
(35%)

NOTE: first & last are not necessarily the same as what is returned by
a container’s begin() and end() methods! The only thing we suppose is
that the container is some sort of a sequence (e.g., vector, list,
etc.) and that first is an iterator which points to an element which
comes before the one pointed to by last. You must not dereference last
because it might be the result of end()!

Here’s my attempt

template<typename Iter, typename Obj>
Iter find_element(Iter iter1, Iter iter2, Obj &obj){
 for(p = iter1; p != iter2; p++){
  if((*p) == obj){
   return p;
  }
 return iter2;
 }  
}

Is this attempt correct? Is the return type suitable for the function or have I got the wrong idea?

Answer 1

Yes, your code is correct. I would perhaps only change Obj &obj to Obj const &obj.

And you ought to have declared p.

More nitpicking: with generic iterators usually the form ++p is preferred.

My variant (basically the same):

template<typename Iter, typename Obj>
Iter find_element(Iter iter1, Iter iter2, Obj const &obj)
{
    for(; iter1 != iter2; ++iter1)
    {
        if(*iter1 == obj)
            break;
    }
    return iter1;
}