Beginning Programming with C++ For Dummies®

Chapter 30. Overloading Assignment Operators

In This Chapter

• Overloading operators — in general, a bad idea

• Overloading the assignment operator — why that one is critical

• What to do when you just can't be bothered with writing an assignment operator

The little symbols like +, -, =, and so on are called operators. These operators are already defined for the intrinsic types like int and double. However, C++ allows you to define the existing operators for classes that you create. This is called operator overloading.

Operator overloading sounds like a great idea. The examples that are commonly named are classes like Complex that represent a complex number. (Don't worry if you don't know what a complex number is. Just know that C++ doesn't handle them intrinsically.) Having defined the class Complex, you can then define the addition, multiplication, subtraction, and division operators (all of these operations are defined for complex numbers). Then you write cool stuff like:

Complex c1(1, 0), c2(0, 1);
Complex c3 = c1 + c2;

Overloading operators turns out to be much more difficult in practice than in theory. So much so that I consider operator overloading beyond the scope of this book with two exceptions, one of which is the subject of this chapter: overloading the assignment operator. The second operator worth overloading is the subject of the next chapter.

Overloading an Operator

C++ considers an operator as a special case of a function call. It considers the + operator to be shorthand for the ...