Discussion Questions, Lecture 1

Discussion Questions / Events

Homework 1 related issues

1:40 - 7:20
Hal answers a bunch of good student questions about HW1:
• What if I want to add additional support functions, like sorting, to my program? In which file do I put the headers for those functions?
• Can I use assert() statements?
  Warning! the body (argument) of an assert() statement is not executed in Release mode, so don't include any statements with side effects inside an assert().
• How can I format text in colums the way it is formatted in the sample solution?
  Hal writes on the overhead: cout << "stuff" << '\t' << "more stuff";
• What can I do to avoid the program window's disappearing at the end of execution?
• What's the difference between the single and double quotes (see above)?
  note: You'll see strings soon in this course.




Motivation for and generals of object (class) programming

7:20
Beginning of slide-related lecture material


8:40
What would be an example of a programmer looking at a class interface, rather than looking at the implementation of that class?


9:30
What do you think is meant by 'client'? How does this relate to the previous question?


10:15
Define the difference: Public vs. private;
Define the difference: Type vs. instance.


14:35
What's the difference between the specification (.h) and the implementation (.cpp) of a class? Think of forward-declared function headers in C.


15:41
In the class declaration in slide 13, which data members / member functions can be used by a client?



Member functions introduced:

18:46
What does it mean for a name of a function to be 'local' to a certain class? What would happen if the scope-limited names didn't exist? Where have you seen names that are local to a scope in C?


20:30
Hal writes a1.deposit(100) on the overhead.


20:41
(Hal's question:) What balance are we referring to (in the BankAccount::deposit() function as invoked by the above call)?


23:28
What would be the state of variables a1 & a2 after the following code is executed?
a1.init("Perkins");
a1.deposit(100);
a2=a1;



Dealing with the possibility of multiple inclusion of files

26:40
(Hal's question:) What's the problem with the code & file structure as illustrated on slide 18?


28:30
This would be a good time to review how #include works (textual substitution before compilation)


32:40
Write over the files on slide 18 with the new multiple inclusion protection. Then 'play preprocessor': start with main, keep track of what symbols are defined (or not), and perform the textual substitution to produce a document ready for compilation.


34:00
Can you use BANKACCOUNT_H later on in your code (inside main)?

Constructors

37:35
(Hal's question:) Why isn't it good to use a value without initializing it? What would the result of cout << sum; be?


40:15
Please do stress that students need to test their programs in Release mode (other reasons include array 'padding' that prevents scribbling other values)


47:40
Slide 35's last example is not an example of the constructor being invoked (the example's inclusion is a mistake). It is the copy constructor that gets called (covered in a later lecture).