Scope Resolution Operator (::)
Ternary or Conditional Operator (?:)
Member Access or Dot operator (.)
Pointer-to-member Operator (.*)
Object size Operator (sizeof)
Object type Operator(typeid)

could not be overloaded in C++ language. Attempting to overload these operators above will cause serious programming issues. For instance, overloading a dot operator may cause error because it has the same technique as the arrow operator(->). As another example, sizeof could not be given a different meaning without violating basic programming rules.