std::vector::erase(item) needs assignment operator to be defined for item?

Question

I have a class C which does not define operator=. I have am trying to use a vector like so: std::vector<std::pair<C,D>> vec;. Now, my problem is that I am not able to erase the pair after I am done with it. The compiler complains of missing operator= for C. Can I not have a vector of a class which does not have this operator? How do I get around this? I cannot add assignment to C. This is the error I get:

error C2582: 'operator =' function is unavailable in 'C'    C:\...\include\utility  196 1   my-lib

This is my code:

void Remove(const C& c) 
{
    auto i = cs_.begin();
    while( i != cs_.end()) {
        if (i->first == c) {
            cs_.erase(i);  // this is the problem
            break;
        }
        i++;
    }
 }

where cs_ is:

std::vector<std::pair<C,D>> cs_;

Answer 1

The reason is that erase will reallocate your objects if you erase a different position than std::vector::end(). A reallocation implicates copying.

Notice that a vector of an uncopyable type is only partially useable. Before we had emplace() (pre-C++11) it was even impossible. If your class is however copyable, why dont you define an assignment operator then?

A workaround could be a vector of smartpointers (or normal pointers) like std::vector<std::unique_ptr<C>>