Book: Starting out with C ++ early objects. 9th

"Create a subclass of the abstract filter class of programing challenge 5 that replaces every line break in a file with a single space"

PC5 file filter reads an input file, transforms it in some way, and writes the results to an output file. Write an abstract file filter class that defines a pure virtua l function for

transforming a character. Create one subclass of your file filter class that performs encryption, another that transforms a file to all uppercase, and another that creates an unchanged copy of the original file.

The class should have a member function void doFilter(ifstream &in, ofstream &out)

that is called to perform the actual filtering. The member function for transforming a single character shou ld have the prototype char t ransform(char ch)

The encryption class should have a constructor that takes an integer as an argument and uses it as the encryption key. */