C++11: =delete

Specifying =delete for any of the compiler-generated constructors or assignment operators, makes them unavailable. Here is an example:

#include <iostream>
class A
{
 public:
  A() {std::cout << "Default CTOR called; ";}
  A(const A& a) = delete;
};
int main()
{
  A a1;
  // A a2(a1); // This line does not compile because of " = delete' above.
  return 0;
}
// Output: Default CTOR called

Reference: https://isocpp.org/wiki/faq/cpp11-language-classes#default-delete