override specifier (since C++11)
From cppreference.com
C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
C++ language
General topics
Conditional execution statements
Iteration statements (loops)
Jump statements
Dynamic exception specifications (until C++17*)
noexcept specifier (C++11) Exceptions
Namespaces
Types
Specifiers
User-defined (C++11)
Utilities
Attributes (C++11)
Types
Type alias declaration (C++11)
Casts
Memory allocation
Class-specific function properties
Special member functions
Miscellaneous
Classes
General
Class property specifiers (C++26)
Members
Default member initializer (C++11)
Special member functions
Move constructor (C++11)
Move assignment operator (C++11)
Inheritance
override specifier (C++11)final specifier (C++11)Specifies that a virtual function overrides another virtual function.
Contents
[edit] Syntax
The identifier override, if used, appears immediately after the declarator in the syntax of a member function declaration or a member function definition inside a class definition.
declarator virt-specifier-seq (optional) pure-specifier (optional)
(1)
declarator virt-specifier-seq (optional) function-body
(2)
1) In a member function declaration,
override may appear in virt-specifier-seq immediately after the declarator, and before the pure-specifier, if used.2) In a member function definition inside a class definition,
override may appear in virt-specifier-seq immediately after the declarator and just before function-body.In both cases, virt-specifier-seq, if used, is either override or final, or final override or override final.
[edit] Explanation
In a member function declaration or definition, override specifier ensures that the function is virtual and is overriding a virtual function from a base class. The program is ill-formed (a compile-time error is generated) if this is not true.
override is an identifier with a special meaning when used after member function declarators; it is not a reserved keyword otherwise.
[edit] Keywords
[edit] Example
Run this code
#include <iostream> struct A { virtual void foo(); void bar(); virtual ~A(); }; // member functions definitions of struct A: void A::foo() { std::cout << "A::foo();\n"; } A::~A() { std::cout << "A::~A();\n"; } struct B : A { // void foo() const override; // Error: B::foo does not override A::foo // (signature mismatch) void foo() override; // OK: B::foo overrides A::foo // void bar() override; // Error: A::bar is not virtual ~B() override; // OK: `override` can also be applied to virtual // special member functions, e.g. destructors void override(); // OK, member function name, not a reserved keyword }; // member functions definitions of struct B: void B::foo() { std::cout << "B::foo();\n"; } B::~B() { std::cout << "B::~B();\n"; } void B::override() { std::cout << "B::override();\n"; } int main() { B b; b.foo(); b.override(); // OK, invokes the member function `override()` int override{42}; // OK, defines an integer variable std::cout << "override: " << override << '\n'; }
Output:
B::foo(); B::override(); override: 42 B::~B(); A::~A();
[edit] See also
final specifier (C++11)
declares that a method cannot be overridden or a class be derived from[edit]