Daily C++ Interview

Function overriding is a term related to polymorphism. If you declare a virtual function in a base class with a certain implementation, in a derived class you can override it's behaviour in case you uses the very same signature. In case, the virtual keyword is missing in the base class, it's still possible to create a function with the same signature in the derived class, but it doesn't override it. Since C++11 there is also the override specifier which helps you to make sure that you don't mistakenly failed to override a base class function. You can find [more details here.

Function overriding enables you to provide specific implementation of the function that is already defined in its base class.

On the other hand, overloading has nothing to with polymorphism. When you have two functions with the same name, some return type, but different number or types of parameters, or qualifiers.

Here is an example for overloading based on parameters

void myFunction(int a);
void myFunction(double a);
void myFunction(int a, int b);

And here is another example based on qualifiers:

class MyClass {
public:
  void doSomething() const;
  void doSomething();
};

Or actually, it possible to overload your function based on whether their hosting objects are rvalue of lvalue references.

class MyClass {
public:
  // ...
  void doSomething() &; // used when *this is a lvalue
  void doSomething() &&; // used when *this is a rvalue
};

You can learn more about this here.