You are overloading << operator as a member function, therefore, the first parameter is implicitly the calling object. You should either overload it as friend function or as a free function. For example: overloading as friend function. However, the canonical way is to overload it as free function. You can find very good information from this post: C++ operator overloading
The problem is that you define it inside the class, which a) means the second argument is implicit (this) and b) it will not do what you want it do, namely extend std::ostream. You have to define it as a free function:
operator+() should not return a reference type as it is a new (locally declared) instance that holds the result of the operation.
As you’ve found, JavaScript doesn’t support operator overloading. The closest you can come is to implement toString (which will get called when the instance needs to be coerced to being a string) and valueOf (which will get called to coerce it to a number, for instance when using + for addition, or in many cases … Read more
The problem is that you declared operator>> and operator<< as non-member functions, but defined as a member function. This should fix that problem (but open another set of problems). So instead of implement as : Also, take a note that you declared functions as : but defined as (therefore you changed the signature) : Proper way is to declare … Read more
Use std::ostream and std::istream everywhere. ostream and istream are in namespace std
You are missing class name: This is global operator, = cannot be global: You must define this as class function:
The error is actually “lvalue required as left operand of assignment”. It means that your a[i][j] is giving you a temporary object. This happens when you return from a function by value. A function call that returns by value is an rvalue expression, and you cannot use an rvalue expression as the left operand of an assignment. You need to … Read more
There are no problems with the second version of the assignment operator. In fact, that is the standard way for an assignment operator. Edit: Note that I am referring to the return type of the assignment operator, not to the implementation itself. As has been pointed out in comments, the implementation itself is another issue. … Read more