Instructions: This homework assignment covers some basics
of linked lists in C++. The answers to
these questions can be determined from the lecture notes and the assigned
readings in the text and Parlante.
Opscan forms will be
passed out in class. Write your name and
code your ID number on the Opscan form.
Turn in your completed Opscan at class on the day specified below. No late Opscans will be accepted.
For
questions 1 through 5 determine what the execution of the given code fragment
would do, assuming the following list structure as your starting point (for
each question):
struct ListNode {
int Element;
ListNode* Next;
};
ListNode *Head, *p, *q, *t;
Match each code fragment to one of the
choices given on page 2.
1. *(q->Next) = *p;
delete
q->Next;
2. p = Head;
Head = p->Next;
delete p;
p = q->Next;
3. *q
= *p;
q->Element = p->Element - 24;
p->Next = q->Next->Next;
4. delete (*q->Next);
5. Head->Next = NULL;
t = Head;
Head = p->Next;
Head->Next = p;
p->Next = q;
q->Next = t;
t = NULL;
Choose from the following
answers. Question marks (??) indicate
the pointer has an unknown, or invalid, value.
1)
2)
3)
4)
5)
6)
7)
8)
9) The given code contains a syntax error.
10) None of these
For questions 6
through 10, assume the class LinkNode
from the course notes, plus the class ItemType
and pointers defined below:
class
ItemType {
private:
int Value;
public:
ItemType() {Value = 0;}
ItemType(int newValue) {Value = newValue;}
void setValue(int newValue) {Value =
newValue;}
int
getValue() const {return Value;}
};
LinkNode
*Head, *P, *Q, *T=NULL;
Assume the following initial list structure for each
question:
Determine
what the execution of the given code fragment would do, assuming the initial
list structure given above as your starting point for each question. Match each code fragment to one of the
choices given on page 4.
6. Head
= Q->getNext();
7. P->setData(Head->getData());
Head->setData(Q->getData().getValue()-25);
8. Head->setNext(P);
P->getNext()->setNext(Q);
Q->setData(P->getNext()->getNext()->getData());
9. Head->setNext(Q->getNext()->getNext());
T = Q->getNext();
Q->getNext()->setNext(Q);
Q->setNext(P->getNext());
P->getNext()->setNext(P);
P->setNext(Head);
Head = T;
T = NULL;
10. delete Head;
Head = Q->getNext();
1)
2)
3)
4)
5)
6)
7)
8) The given code contains a syntax error.
9) None of these.
For questions 11 through 15, assume the classes LinkNode and LinkList from the course notes (with the necessary
logical fixes in LinkList), and the class Contact defined below:
class
Contact {
private:
string Name;
string Phone;
public:
Contact();
Contact(string initName,
string initPhone);
string getName() const;
string getPhone() const;
void
setName(string newName);
void
setPhone(string newPhone);
bool operator==(const Contact&
Other);
void printContact(ostream& Out);
};
Contact::Contact()
{
Name
= "Anonymous";
Phone = "BR-549";
}
Contact::Contact(string
initName,
string initPhone) {
Name
= initName;
Phone = initPhone;
}
string
Contact::getName() const {
return Name;
}
string
Contact::getPhone() const {
return Phone;
}
void
Contact::setName(string newName) {
Name = newName;
}
void
Contact::setPhone(string newPhone) {
Phone = newPhone;
}
bool
Contact::operator==(const Contact&
Other) {
return ( (Name == Other.Name) &&
(Phone == Other.Phone) );
}
void
Contact::printContact(ostream& Out) {
Out << Name
<< setw(30 - Name.length())
<< ' '
<< Phone
<< endl;
}
Assume that
Contact has been typedef’d to be synonymous with ItemType.
Consider the problem of implementing a function (not a member function
of any of the classes involved) to search a LinkList
to update the phone number for a given Contact object:
11. How
should be blank in line 1 be filled?
12. How
should be blank in line 2 be filled?
13. How
should be blank in line 6 be filled?
14. If
the last parameter, NewNum,
were omitted and the C
contact parameter actually contained the new “updated” phone number would the
function still work correctly?
15. Is
Boolean Short-Circuiting necessary in the compiler for the above function to
work correctly?
For questions 16 through 20, consider a C++
program composed of two cpp files and two corresponding header files, as
shown below. All function calls are
shown, as are all include directives, but type declarations and
function prototypes are not. In the
source files, there should be only one physical occurrence of a function
prototype, and one physical occurrence of a type declaration. Preprocessor directives for separate
compilation, (#ifndef
#define #endif), are not shown, but you should assume they are used wherever needed.
// main.cpp
#include "Foo.h"
. . .
int main() {
Widget
R; // struct type Widget
Foo(R);
. . .
}
// Foo.h
#include "main.h"
. . .
// Foo.cpp
#include "Foo.h"
. . .
void Foo(Widget& Data) {
. . .
Data =
Bar();
. . .
}
Widget Bar() {
. . .
}
One of our goals is for the two cpp
files to be separately compilable. That
is, we want to be able to compile main.cpp and Foo.cpp independently of each other. We also have the goal that no identifier
declaration should be made available in a place where it is not needed.
Choose from the following answers:
1) main.h
2) main.cpp
3) Foo.cpp
4) Foo.h
5) Any
of these
6) main.h
or main.cpp
7) Foo.cpp or Foo.h
8) main.h,
Foo.h
or Foo.cpp
9) main.h,
main.cpp or Foo.h
10) None
of these
16. In
order for the file main.cpp to compile separately, where could the prototype for the function Foo() be placed?
17. In
order for the file main.cpp to compile separately, and for the most
sensible organization of the code, where should the prototype
for the function Foo() be placed?
18. In
order for the file Foo.cpp to compile separately, where could the prototype for the function Bar() be placed?
19. In
order for the file Foo.cpp to compile separately, and for the most
sensible organization of the code, where should the prototype
for the function Bar() be placed?
20. In
order for both of the files main.cpp and Foo.cpp to compile separately, and for the most
sensible organization of the code, where should the
declaration for the type Widget be placed?
