What is the override keyword in C used for

Question

I am a beginner in C    I have come across override keyword used in the header file that I am working on  May I know  what is real use of override  perhaps with an example would be easy to understand

User · Answer

override is a C  11 keyword which means that a method is an  override  from a method from a base class  Consider this example      class Foo         public          virtual void func1             class Bar   public Foo         public          void func1   override         If B  func1   signature doesn t equal A  func1   signature a compilation error will be generated because B  func1   does not override A  func1    it will define a new method called func1   instead

User · Answer

And as an addendum to all answers  FYI  override is not a keyword  but a special kind of identifier  It has meaning only in the context of declaring defining virtual functions  in other contexts it s just an ordinary identifier  For details read 2 11 2 of The Standard    include  lt iostream gt   struct base       virtual void foo     0      struct derived   base       virtual void foo   override               std  cout  lt  lt    PRETTY FUNCTION    lt  lt  std  endl            int main         base  override   new derived        override- gt foo        return 0      Output   zaufi gentop  work tests   g   -std c  11 -o override-test override-test cc zaufi gentop  work tests     override-test virtual void derived  foo

User · Answer

Wikipedia says      Method overriding  in object oriented programming  is a language feature that allows a subclass or child class to provide a specific implementation of a method that is already provided by one of its superclasses or parent classes     In detail  when you have an object foo that has a void hello   function   class foo       virtual void hello       Code   printf  Hello         A child of foo  will also have a hello   function   class bar   foo          no functions in here but yet  you can call        bar hello       However  you may want to print  Hello Bar   when hello   function is being called from a bar object  You can do this using override  class bar   foo       virtual void hello   override     Code   printf  Hello Bar

User · Answer

The override keyword serves two purposes     It shows the reader of the code that  this is a virtual method  that is overriding a virtual method of the base class   The compiler also knows that it s an override  so it can  check  that you are not altering adding new methods that you think are overrides     To explain the latter   class base     public      virtual int foo float x    0        class derived  public base      public       int foo float x  override            OK    class derived2  public base      public       int foo int x  override            ERROR      In derived2 the compiler will issue an error for  changing the type   Without override  at most the compiler would give a warning for  you are hiding virtual method by same name

[c++] What is the 'override' keyword in C++ used for?

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