Chapter 11, Problem 4PP

Enhance the definition of the class StringVar given in Displays 11.11 and 11.12by adding all of the following:

• Member function copyPiece, which returns a specified substring; member function oneChar, which returns a specified single character; and member function setChar, which changes a specified character
• An overloaded version of the == operator (note that only the string values have to be equal; the values of maxLength need not be the same)
• An overloaded version of + that performs concatenation of strings of type StringVar
• An overloaded version of the extraction operator >> that reads one word (as opposed to inputLine, which reads a whole line)

  If you did the section on overloading the assignment operator, then add it as well. Also write a suitable test program and thoroughly test your class definition.