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Using override with virtual in C++ 11

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The specifier override has a special meaning in C++11 onwards, if appended at the end of function signature. This signifies that a function is

There is no run time significance of this specifier as is mainly meant as an indication for compilers

The example below will demonstrate the change in behaviour with our without using override.

Without override: 

#include <iostream>

struct X {
    virtual void f() { std::cout << "X::f()\n"; }
};

struct Y : X {
	// Y::f() will not override X::f() because it has a different signature, 
	// but the compiler will accept the code (and silently ignore Y::f()). 
	virtual void f(int a) { std::cout << a << “\n”; }
};

With override: 

#include <iostream>

struct X {
    virtual void f() { std::cout << "X::f()\n"; }
};

struct Y : X {
	// The compiler will alert you to the fact that Y::f() does not 
	// actually override anything. 
	virtual void f(int a) override { std::cout << a << “\n”; }
};

Note that override is not a keyword, but a special identifier which only may appear in function signatures. In all other contexts override still may be used as an identifier: 

void foo() {
	int override = 1; // OK. 
	int virtual = 2; // Compilation error: keywords can’t be used as identifiers.
}
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Virtual member functions:
* Syntax
* Remarks
* Using override with virtual in C++ 11
* Virtual vs non-virtual member functions
* Final virtual functions
* Behaviour of virtual functions in constructors and destructors
* Pure virtual functions
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0 Getting started
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62 RAII
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81 Type erasure
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84 RTTI
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86 Expression templates
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91 Date and time with std::chrono
92 Trailing return type
93 Function template overloading
94 Common compile linker errors
95 Design patterns
96 Optimizations
97 Compiling and building
98 Type traits
99 One definition rule
100 Unspecified behavio
101 Argument dependent name lookup
102 Attributes
103 Internationalization
104 Profiling
105 Return type covariance
106 Non-static member functions
107 Recursion
108 Callable objects
109 Constant class member functions
110 C++ vs. C++ 11 vs C++ 17
111 Inline functions
112 Client server examples
113 Header files
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115 Refactoring techniques
116 Parameter packs
117 Iteration
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119 C++ 11 memory model
120 Build systems
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122 Type inference
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124 Storage class specifiers
125 Alignment
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127 Linkage specifications
128 Curiusly recurring template pattern
129 Using declaration
130 Typedef and type aliases
131 Layout of object types
132 C incompatibilities
133 Optimization
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135 Thread synchronization
136 Debugging
137 Futures and promises
138 More undefined behaviors
139 Mutexes
140 Recursive mutex
141 Unit testing
142 decltype
143 Digit separators
144 C++ Containers
145 Arithmetic meta-programming
146 Contributors