CSE 143 2000WI Midterm 1 Version B Page 10 of 1
Part I: 12 Multiple choice questions (2 points each):
Answer all of the following questions. READ EACH QUESTION CAREFULLY. Fill the correct bubble on your mark-sense sheet. Each correct question is worth 2 points. Choose the one BEST answer for each question. Assume that all given C++ code is syntactically correct unless a possibility to the contrary is suggested in the question.
Remember not to devote too much time to any single question, and good luck!
1. / Consider the following program.#include <iostream>
using namespace std;
int * f (int n) {
int a[10];
for (int i = 0; i < 10; i++)
a[i] = i*n;
return a;
}
void main() {
int j, k;
int * p;
j = 12;
p = f(j);
for (k = 0; k < 10; k++) {
cout < p[k];
}
cout < endl;
}
Is this a legal C++ program and does it execute without errors?
A. / Fails to compile because variable p in the main program is not an array, and cannot be subscripted.
B. / Fails to compile because "p=f(j);" is an array assignment, and array assignments are not supported in C/C++.
C. / Fails during execution with a subscript-out-of-range error.
D. / Might appear to work, but is not correct because it uses a dangling pointer (pointer to no-longer-allocated storage).
E. / None of the above (either the program works fine, or it fails for some reason not given here).
2. / Suppose we have the following partial class definitions:
class Time { // wall clock time
public:
// construct Time object with initial time hh:mm
Time(int hh, int mm);
// return hour part of this Time object
int hours();
// return minute part of this Time object
int min();
...
private:
// representation of Time objects
int hr, min; // hours and minutes, where 0 <= min <= 60
};
class Event { // an event in the calendar
public:
// Construct Event with description d and Time t
Event(string d, Time t);
// Advance time of this Event by given number of minutes
void advanceTime(int minutes);
...
private:
// representation of an event
string what; // event description
Time when; // time of event
};
Now, here is a proposed implementation of the advanceTime method, which adds the given number of minutes to the Time part of an event
// Advance time of this Event by given number of minutes
void Event::advanceTime(int minutes) {
when.min = when.min + minutes;
while (when.min > 60) {
when.hr++;
when.min = when.min - 60;
}
}
Is this function
A. / Correct, works fine
B. / The calculation is correct, but the variable when in Event::advanceTime has not been declared properly (i.e., the compiler will complain about an undeclared variable).
C. / The calculation is correct, but the function is illegal because it attempts to access private variable when, which is not accessible inside function advanceTime.
D. / The calculation is correct, but the function is illegal because it attempts to access the fields of variable when.
E. / None of the above
3. / Suppose we have a class Thing declared in file thing.h as follows.
class Thing {
public:
// initialize this Thing when it is constructed
Thing();
// other public operations
...
private:
// private representation
...
};
Now suppose we execute the following main program
#include "thing.h"
int main() {
Thing it;
Thing them[2];
// quit without doing anything else
return 0;
}
How many times is the default (null) constructor for class Thing executed?
A. / 0
B. / 1
C. / 2
D. / 3
E. / 4
4. / Consider the following program fragment:
#include <iostream>
using namespace std;
int* a = new int[10];
for(int i = 0; i<10; i++) a[i] = i;
int* b = &a[2];
cout < b[3];
What will this program fragment display?
A. / 2
B. / 3
C. / 5
D. / Nothing. It is not a legal C++ program.
E. / This is a legal program, but the value printed cannot be determined from the code given here
5. / What does the following program output? (Hint: you may find it very helpful to diagram the use of pointers and memory to follow what is happening here.)
#include <iostream>
using namespace std;
void mystery(int* pInt)
{
pInt = new int;
*pInt = 143;
cout < *pInt < " ";
}
void main()
{
int i = 142;
int* pInt = &i;
mystery(pInt);
cout < *pInt < " ";
}
A. / 143 142
B. / 142 143
C. / 142 142
D. / 143 143
E. / No output, the code is erroneous
6. / Consider the following class definition which represents a geometric Point:
class Point {
private:
// representation is here
public:
Point(double x, double y);
double getX();
double getY();
double distanceTo(Point other); // distance between this point and the other
void paint(); // paint the Point on the screen
};
From the definition of Point above we know that the representation of a Point must be:
A. / A point in the x-y coordinate system.
B. / Two variables of type double: one for the x coordinate, and one for the y coordinate.
C. / A dynamically allocated array.
D. / A polar representation: an angle and a distance from the origin.
E. / There is no way of knowing.
Consider the following class definition, which represents an Employee, and the implementation of one of the methods:
class Employee {
private:
string name;
…
public:
…
bool equals(Employee& other);
};
bool Employee::equals(Employee& other) { return name == other.name; }
Is there anything wrong with the implementation of Employee::equals?
A. / There is no problemB. / The equals method as implemented does not return value of type bool.
It returns a –1, 0, or 1.
C. / This method is useless since one Employee object could never equal another.
D. / The use of other.name is not valid since other is a reference parameter.
E. / The use of other.name is not valid because it does not belong to the local Employee object associated with the function call.
8. / Suppose you have the following program.
#include <iostream>
using namespace std;
int main() {
int i, j, k;
i = 1; j = 2; k = 3;
cin > i > j > k; // Input Statement
return 0;
}
Suppose we execute this program and the user enters the following input
17 xvii 42
What are the values stored in variables i, j, and k after execution of the input
statement (cin > ...)?
A. / i = 1, j = 2, k = 3
B. / i = 17, j = 2, k = 3
C. / i = 17, j = unknown, k = 3
D. / i = 17, j = 2, k = 42
E. / i = 17, j = unknown, k = 42
9. / Suppose we see the following data structure definition in a program:
const int MAX_INPUT = 100; // maximum number of items in input
struct InputList { // buffer containing numbers to be processed
int input[MAX_INPUT]; // input numbers
int current; // current input position
int nItems; // number of input items
};
What do we know *for certain* about this data structure, given the above
definition?
A. / Array elements input[current]..input[nItems] contain input items that have not yet been processed.
B. / Array elements input[current+1]..input[nItems] contain input items that have not yet been processed.
C. / Array elements input[current]..input[nItems-1] contain input items that have not yet been processed.
D. / Array elements input[current+1]..input[nItems-1] contain input items that have not yet been processed.
E. / It is impossible to answer the question with certainty given the data structure and supplied comments.
10. / Consider the following program:
#include <iostream>
using namespace std;
int foo(int& x, int& y) {
x = 2*y;
y = y + x;
return x + 5;
}
void main() {
int a = 3, b = 7;
a = foo(a, b+4);
cout < a < “ “ < b;
}
What does this program output?
A. / 27 33
B. / 27 7
C. / 19 14
D. / 19 18
E. / Nothing. It is not a legal C++ program.
11. / What output does the following program produce?
#include <iostream>
using namespace std;
void f(int &a, int b, int &c) {
b = a - c;
a = b * c;
}
int main() {
int a = 10;
int b = 15;
f(b,a,a);
cout < a < ' ' < b < endl;
}
A. / 10 50
B. / 50 10
C. / 10 15
D. / 10 150
E. / none of the above
12. / Consider the following program:
#include <iostream>
using namespace std;
void bar(int* a) {
for(int j = 0; j < 4; j++)
a[j] = 4 – j;
}
void main() {
int* a = new int[4];
bar(a);
for(int i = 3; i >= 0; i--)
cout < a[i] < “ “;
}
What will this program output?
A. / 0 1 2 3B. / 1 2 3 4
C. / 3 2 1 0
D. / 4 3 2 1
E. / Cannot tell from the given program.
Part II: Programming Question 1 (10 points)
This question does not involve C++ classes with member functions. It does, however, use the C++ string class.
In this problem, you are to write some code to process a data structure containing information about the animals in various zoos around the world. The data structures are defined as follows:
#include <string>
#include <iostream>
using namespace std;
struct Zoo { // information about a single zoo:
string name; // zoo name
int llama; // number of llamas in this zoo
int giraffe; // number of giraffes in this zoo
int lion; // number of lions, etc.
int tiger; // (similarly for each named animal)
int kangaroo;
int elephant;
int bear;
int donkey;
int wombat;
};
const int MAX_ZOOS = 1742; // maximum # of zoos in list
struct ZooList { // information about a collection of zoos:
int nZoos; // # of zoos currently in the list
Zoo z[MAX_ZOOS]; // zoo information is stored in z[0..nZoos-1]
};
(a) Complete the definition of the function makeEmptyZooList that sets its ZooList parameter to an empty list (containing no Zoos). Your code should perform all of the initialization actually needed to solve the problem, and no more.
// set ZooList z to an empty list
void makeEmptyZooList(ZooList &z) {
z.nZoos = 0;
}
(b) ["Lions and tigers and bears, oh my!!"]
An Interesting Zoo is one whose collection contains at least one each of lions, tigers, and bears (i.e., one or more of each of these three kinds of animals). Complete the following function definition so it prints on cout the name(s) of all interesting zoos in its ZooList parameter, one zoo name per output line.
// print names of zoos from list z that have at least one lion, tiger, and bear
void printInterestingZoos(ZooList &z) {
for (int k = 0; k < z.nZoos; k++)
if (z.z[k].lion > 0 & z.z[k].tiger > 0 & z.z[k].bear > 0)
cout< z.z[k].name < endl;
}
Programming Question 2 (10 points)
The boss would like to add a feature to the help-desk scheduling program to print a report listing people who are working too many shifts.
For this problem, complete the definition of function reportOverworked, which, when it is executed, prints a list of all employees who are working six or more shifts during the week.
Example: Suppose the shift schedule contains the following:
Monday: Alice Bob
Tuesday: Bob Ralph
Wednesday: Alice Fred Bob
Thursday: Alice Susan Bob
Friday: George Bob Alice
Saturday: Alice Ralph
Sunday: Alice Bob
With this schedule, reportOverworked should print the following (exact format and order of names does not matter).
Overworked Employees: Alice Bob
Your code should use the class definitions for Homework 2, which are printed for reference at the end of this problem. Notice that these are the same as the ones given in the sample solution, except that the shifts in the schedule are not necessarily sorted when reportOverworked is called.
Hint: Be sure to take advantage of any available functions in the classes to simplify your code.
// reportOverworked - print names of employees working 6 or more shifts
void Schedule::reportOverworked() {
string currentEmployee; // name of and # of shifts worked by
int nShifts; // current employee in the list
string employee; // name of employee for next shift in list
// If schedule is empty, quit without examining it
if (size <= 0)
return;
// ensure schedule sorted
sortByName();
// count first shift for first employee
currentEmployee= shifts[0].getEmployee().getName();
nShifts = 1;
// examine and count remaining shifts
for (int k = 1; k < size; k++) {
// if this is another shift for the same employee, count it
// and print name if this is the 6th shift for this person;
// otherwise, set count to 1 for new employee.
employee = shifts[k].getEmployee().getName();
if (employee == currentEmployee) {
nShifts++;
if (nShifts == 6)
cout < employee < ' ';
} else {
nShifts = 1;
currentEmployee = employee;
}
}
Reference information: Class Definitions for help-desk program
// description of one help desk employee and his/her skills