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# override specifier

From cppreference.com
< cpp‎ | language

Specifies that a virtual function overrides another virtual function.

### [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.

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, `override` may appear in virt-specifier-seq immediately after the declarator and just before function-body (which may begin with a member initializer list)

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` ensures that the function is virtual and is overriding a virtual function from the 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's not a reserved keyword otherwise.

### [edit] Example

    struct A
    {
        virtual void foo();
        void bar();
    };

    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: B::bar is not virtual
    };

### [edit] See also

- final specifier (since C++11)

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