Streams

The Inheritance Hierarchy of Stream Classes

The standard cin and cout objects belong to specialized system-dependent classes with nonstandard names.
You can assume that cin belongs to a class that is derived from istream and cout belongs to a class derived from ostream.
Take advantage of the inheritance relationships between the stream classes whenever you write functions with stream parameters.
```
double rand_data(istream& in);
```
You can now pass parameters of types derived from istream, such as a ifstream object or cin.
```
max = read_data(infile);
max = read_data(cin);
```
Remember to pass the streams by reference to avoid slicing.