Assigning or inserting class objects in unordered_map

I have a class: class1 with a private member variable:

std::unordered_map<std::string, class2> s_list;

I am trying to insert or assign objects of class2 in the above s_list.

The class2 has a copy constructor of the form:

class2::class2(const class2& obj)
{
    x = obj.x;
    y = obj.y;
}

It also has another constructor:

class2::class2(std::string x1, double y1)
{
    x = x1;
    y = y1;
}

Inside one of the functions of class1, I have the following lines:

class2 s_obj(x1, y1);
s_list[x1] = s_obj;

However, it throws the error:

error: no matching function for call to ‘class2::class2()’
         second(std::forward<_Args2>(std::get<_Indexes2>(__tuple2))...)
                                                                      ^

What am I missing here?

You are missing a default ctor. In an unordered_map if there is no match for a value of a key it creates a default one and returns a reference to it.

Consider the subscript operator [].See Here. Closely observe the return T&

If you do s_list["foo"] and there is no value associated with "foo" it creates a entry in the unordered_map with key "foo" and returns a reference to the default value by callings its default ctor.

In your class2 you dont have one. To fix it create a default ctor

class class2 // horrible name btw
{
   class2() = default;
}

or use insert. Reference