doc:when to use friend,normal,member functions

README.md

@@ -2678,4 +2678,23 @@ int main()
 # Summary of Operator Overloading
 <p align="center">
     <img src="/Some%20extra%20concepts/codeSnaps/summary.png" style="height: 80vh; padding-left: 0vh;">
- </p>
+ </p>
+
+ # Imporatnt Tip:
+ ## When to use a normal, friend, or member function overload
+
+In most cases, the language leaves it up to you to determine whether you want to use the normal/friend or member function version of the overload. However, one of the two is usually a better choice than the other.
+
+When dealing with binary operators that don’t modify the left operand (e.g. operator+), the normal or friend function version is typically preferred, because it works for all parameter types (even when the left operand isn’t a class object, or is a class that is not modifiable). The normal or friend function version has the added benefit of “symmetry”, as all operands become explicit parameters (instead of the left operand becoming *this and the right operand becoming an explicit parameter).
+
+When dealing with binary operators that do modify the left operand (e.g. operator+=), the member function version is typically preferred. In these cases, the leftmost operand will always be a class type, and having the object being modified become the one pointed to by *this is natural. Because the rightmost operand becomes an explicit parameter, there’s no confusion over who is getting modified and who is getting evaluated.
+
+Unary operators are usually overloaded as member functions as well, since the member version has no parameters.
+
+The following rules of thumb can help you determine which form is best for a given situation:
+
+- If you’re overloading assignment `(=), subscript ([]), function call (())`, or member selection (->), do so as a member function.
+- If you’re overloading a unary operator, do so as a member function.
+- If you’re overloading a binary operator that does not modify its left operand (e.g. operator+), do so as a normal function (preferred) or friend function.
+- If you’re overloading a binary operator that modifies its left operand, but you can’t add members to the class definition of the left operand (e.g. operator<<, which has a left operand of type ostream), do so as a normal function (preferred) or friend function.
+- If you’re overloading a binary operator that modifies its left operand (e.g. operator+=), and you can modify the definition of the left operand, do so as a member function.