12/05/05 Lecture Notes CISC105

Exam 1 multiple choice grading

* It has been established that there was _one_ problem with the 
  exam 1 multiple choice grading: some of the grades were originally
  associated with the wrong userids.

  This affected only userids from M through Z. 

* It is possible that there was ALSO a separate problem with one or
  more of the answer keys.    It was not possible to look into that
  until the original problem was solved.

* So, now, please look over your scantron sheet, and compare it with the
  online answer keys.


  If you find a discrepancy, bring it to Prof. Conrad during office hours
  or make an appointment.   SENDING EMAIL IS NOT GUARANTEED TO GET A
  CORRECTION MADE (email is backed up with over 300 unread emails).

E01 19 mc

E02 15 mc


Pass by reference vs. Pass by value

Check out

http://copland.udel.edu/~pconrad/cisc105/05F/examInfo/E02_practiceQuiz/quiz1.html

Then, note the following:


void foo(int w);
int bar(int x);
void fum(int *y);
int fiddle(int *z);


foo and bar are pass by value

fum and fiddle are pass by reference


foo and fum .... what do they have in common?
   they don't return anything... they have a return type of void
  
bar and fiddle .... what do they have in common?
   both return an int value


  int a, b, c, d;

  a = 5;
  b = 6;
  c = 7;
  d = 8;

  b = ____ ( &c);

Which of the functions, foo, bar, fum, fiddle could
be used to fill in the blank?

If you tried to use either foo or fum, you would get a
syntax error... you MUST have a return value if you are
assigning the return value to the left hand side.

  printf("%d\n", ____ (a));

Which one?

   bar


  printf("I'm gonna call a function\n");
  ____ (5);

  This is a trick question.

  But, for sake of argument, which one
  could I call?

  The best answer is foo, because since I'm not
  using the return value, a void function is probably
  called for.

  Second the answer is probably foo because I'm 
  passing in a literal int (5), so I probably a
  parameter of type int.

  However, there are two details:

   * It is possible to call a function that returns
     a value, and ignore the value returned.

     That is, just because someone throws you a ball,
     doesn't mean you have to catch it.