Operator Overloading in C++
Operator overloading is an important concept in C++. It is polymorphism in which an operator is overloaded to give user defined meaning to it. Overloaded operator is used to perform operation on user-defined data type. For example '+' operator can be overloaded to perform addition on various data types, like for Integer, String(concatenation) etc.
Almost any operator can be overloaded in C++. However there are few operator which can not be overloaded. Operator that are not overloaded are follows
- scope operator -
- member selector -
- member pointer selector -
- ternary operator -
Operator Overloading Syntax
Implementing Operator Overloading in C++
Operator overloading can be done by implementing a function which can be :
- Member Function
- Non-Member Function
- Friend Function
Operator overloading function can be a member function if the Left operand is an Object of that class, but if the Left operand is different, then Operator overloading function must be a non-member function.
Operator overloading function can be made friend function if it needs access to the private and protected members of class.
Restrictions on Operator Overloading in C++
Following are some restrictions to be kept in mind while implementing operator overloading.
- Precedence and Associativity of an operator cannot be changed.
- Arity (numbers of Operands) cannot be changed. Unary operator remains unary, binary remains binary etc.
- No new operators can be created, only existing operators can be overloaded.
- Cannot redefine the meaning of a procedure. You cannot change how integers are added.