How to delete the default constructor?

Question

Sometimes I don\'t want to provide a default constructor, nor do I want the compiler to provide a system default constructor for my class. In C++ 11 I can do thing like:

Answer 1

Since c++11, you can set constructor = delete. This is useful in conjunction with c++11's brace initialization syntax {}.

For example:

struct foo {
  int a;
  foo() = delete;
};

foo f{}; // error use of deleted function foo::foo()
foo f{3}; // OK

see https://en.cppreference.com/w/cpp/language/default_constructor#Deleted_implicitly-declared_default_constructor