Rules for overloading operators in C++

Rules for overloading operators

• Only existing operators can be overloaded. New operators cannot be created.
• The overloaded operator must have at least one operand that is of the user-defined type.
• We cannot change the meaning of an operator. That is, we cannot redefine the plus (+) operator to subtract one value from others.
• Overloaded operators follow the syntax rules of the original operators. That cannot be overridden.
• Friend functions cannot be used to overload certain operators like =, ( ), [ ] and >.
• Binary operators such as +, -, *, and / must explicitly return a value
• As described above, all operators cannot be overloaded.
• Unary operators overloaded by means of a member function take no explicit arguments and return no explicit values. But, those overloaded by means of friend function take one argument.
• Binary operators overloaded by means of a member function take one explicit argument. But, those overloaded by means of friend function take two arguments.
• The process of operator overloading generally involves following steps.
• Declare a class whose objects are to be manipulated using operators.
• Declare the operator function, in the public part of the class. It can either normal member function or friend function.
• Define the operator function within the body of a class or outside the body of the class but function prototype must be inside the class body.