| |
 | Overloading Operator + the Right Way
By Danny Kalev, C++ Pro
|
User-defined types such as string, date, complex and file often overload the binary + operator to perform some sort of concatenation, addition or merging of two objects. However, a proper implementation of operator + poses several challenges in terms of design, implementation and performance. In the following sections, I will show how to choose the right strategies for overloading this operator for user-defined types in general.
Consider the following expression:
int x=4+2;
The built-in + takes two operands of the same type, adds them and returns an rvalue 6 which is assigned to x. We can conclude that the built-in + is a binary, symmetric and commutative operator. It produces a result of the same type as its operands'. As a rule, when you overload an operator for a user-defined type, retain the characteristics of the corresponding built-in operator.
Overloading the + operator for a user-defined type is a common programming task. However, since C++ offers several implementation approaches, it's relatively easy to make design mistakes that have adverse effects on code correctness, performance and compatibility with Standard Library components.
Analyze the characteristics of the built-in operator and try to imitate them in the corresponding overloaded operator.
|
|
Find Out More
• All DevX 10-Minute Solutions for C/C++
• DevX Tip: Guidelines for Overloading the + Operator
• DevX Tip: What are Lvalues and Rvalues?
• STL Library Programmer's Guide
 | TALK BACK |
Operator overloading was deliberately omitted from Java because its creators considered it a source of "unnecessary complication." However, C# does support operator overloading, just as does C++. What is your stance regarding operator overloading? Is it an indispensable feature or a source of "unnecessary complication," as Java designers claimed?
 |
|
