C++: A Dialog Programming with the C++ Standard Library

Assignment Operator Issues

Now, let's look at the next line: s = n;. That looks harmless enough; it just copies one string, n, to another string, s. But wait a second; how does the compiler know how to assign a value to a variable of a type we've made up?

Just as the compiler will generate a version of the default constructor if we don't define one, because every object has to be initialized somehow, the ability to assign one value of a given type to a variable of the same type is essential to being a concrete data type. Therefore, the compiler will supply a version of operator =, the assignment operator, if we don't define one ourselves. In Chapter 6, we were able to rely on the compiler-generated operator =, which simply copies every member ...