101
THE CompSci UNIVERSITY OF AUCKLAND
SECOND SEMESTER, 2007
Campus: City
COMPUTER SCIENCE
TEST
Principles of Programming
(Time allowed: 75 MINUTES)
NOTE:
Attempt ALL questions
Write your answers in the space provided
There is space at the back for answers that overflow the allotted space
No calculators are permitted
Surname:
Forenames:
Student ID number:
Login name:
CONTINUED
Question/Answ er Sheet
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CompSci 101 S2 C
SURNAME: ...................................................... FOR EN AMES: ...........................................................
CompSci 101 Test Results
Question
Marks
Out of
Question 1
10
Question 2
5
Question 3
5
Question 4
10
Question 5
20
Question 6
10
TOTA L
60
CONTINUED
Question/Answ er Sheet
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CompSci 101 S2 C
SURNAME: ...................................................... FOR EN AMES: ...........................................................
Question 1 (10 marks)
What is displayed by each of the following pieces of Java program?
a)
System.out.println("\"quote");
"quote
(1 mark)
b)
System.out.println("X" + (2 + 3));
X5
(1 mark)
c)
int value = 13;
System.out.println(value < 6);
false
(1 mark)
d)
int i = 5;
int[] numbers = {4, 2, -7, 5, 1, 6, 3};
System.out.println (numbers[i]);
6
(1 mark)
e)
String name = "banana split";
System.out.println(name.indexOf('n'));
2
(1 mark)
f)
String name = "facile";
System.out.println(name.substring(1, 3));
ac
(1 mark)
g)
String name = "peasy";
System.out.println(name.substring(1));
easy
(1 mark)
h)
int x = 5, y = 4;
System.out.println(Math.max(x, y));
5
(1 mark)
CONTINUED
Question/Answ er Sheet
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CompSci 101 S2 C
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i)
int [] numbers = {2,3,4,5,6,7,8};
System.out.println(numbers[0]*numbers[3]);
10
(1 mark)
j)
String [] strings = {"cat","dog","snake","ocelot"};
System.out.println(strings[2].length());
5
(1 mark)
Question 2 (5 marks)
Add the return type to the following Java methods:
a)
private
int
addNums(int num1, int num2) {
return num1 + num2;
}
(1 mark)
b)
private
void
printNumber(int num) {
System.out.println(num);
}
(1 mark)
c)
private
String
getString(char c) {
return "" + c;
}
(1 mark)
d)
private
double
increase(int num) {
return num + 1.0;
}
(1 mark)
e)
private
boolean
isOdd(int num) {
return ((num % 2) == 1);
}
(1 mark)
CONTINUED
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CompSci 101 S2 C
SURNAME: ...................................................... FOR EN AMES: ...........................................................
Question 3 (5 marks)
a)
Write a Java boolean expression which tests if the value of the int variable, number, is
less than 50.
number < 50
b)
(1 mark)
Write a Java boolean expression which tests if the value of the int variable, number, is
even.
(number%2) == 0
c)
(1 mark)
Write a Java boolean expression which tests if the value of the boolean variable,
isThin, is false
isThin == false
d)
(1 mark)
Write a Java boolean expression which tests if the value of the String variable, name,
has the same characters in the same order as "George".
name.equals("George")
e)
(1 mark)
Write a Java boolean expression which tests if the value of the int variable, number,
is not zero and divides evenly into 500
(number != 0) && ((500 % number) == 0)
(1 mark)
CONTINUED
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CompSci 101 S2 C
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Question 4 (10 marks)
Complete each of the methods below as specified in the comment preceding each method.
a)
// method to find the smallest of three numbers
private int smallest(int x1, int x2, int x3){
return Math.min(x1,Math.min(x2,x3));
}
(2 marks)
b)
// method to decide whether two numbers are in ascending
// order
private boolean areInOrder(int n1, int n2){
return n1 < n2 ;
}
(2 marks)
c)
// method to return the last half of a String (including
// the middle character if the length is odd)
private String lastHalf(String s){
int middle = s.length() / 2;
return s.substring(middle);
}
(2 marks)
d)
// method to tell whether one String, s1, is the first
// part of a longer String, s2 (e.g. isStart("ab","abcd")
// is true, but isStart("ab","acbd") is false
private boolean isStart(String s1, String s2){
int s1Length = s1.length();
String firstPartOfS2 = s2.substring(0,s1Length);
return s1.equals(firstPartOfS2);
}
CONTINUED
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CompSci 101 S2 C
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(2 marks)
e)
// method to display the first parameter, s, the number of
// times given by the second parameter, n. The output
// should all be on one line, with no extra spacing.
private reiterate(String void s, int n){
for (int i=0; i<n; i++){
System.out.print(s);
}
}
(2 marks)
CONTINUED
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CompSci 101 S2 C
SURNAME: ...................................................... FOR EN AMES: ...........................................................
Question 5 (20 marks)
a. Complete the method incomeInRange() which accepts a positive double parameter
income and two double bounds, lower and upper, where lower <= upper. The method
returns the amount of the income that is between the two bounds. You may use if-statements to
answer this question. Do not use Math class methods.
// method to find the income within a range
private double incomeInRange
(double income, double lower, double upper) {
if (income <= lower) {
return 0;
}
if (income > upper) {
return upper - lower;
}
return income - lower;
}
(5 marks)
b. Complete the method called getBoundedInt() which prompts the user to type in an int
value less than the value of the int parameter bound. A user who types a number that is greater
than, or equal to, bound, is continually re-prompted to provide an int value less than bound.
When the user has typed a correct value it is returned as the value of the method. You should make
use of the helper method getUserInt()that reads the user input and returns it as an int
// method to get a bounded int from the user
private int getBoundedInt(int bound) {
System.out.print("Type in a number less than " + bound);
int number = getUserInt();
while (number >= bound){
System.out.print("Type in a number less than " + bound);
number = getUserInt();
}
return number;
}
CONTINUED
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CompSci 101 S2 C
SURNAME: ...................................................... FOR EN AMES: ...........................................................
(5 marks)
c. Complete the method rotateLeft() which accepts a String parameter word, and returns
the String rotated one character to the left, e.g. "luck" gives the result "uckl"
// method to find a word rotated to the left, e.g. "luck"
// gives result "uckl"
private String rotateLeft (String word){
char firstChar = word.charAt(0);
String wordTail = word.substring(1);
return wordTail + firstChar;
}
(5 marks)
d. Complete the method isAllUpperCase() which accepts a String parameter, word, and
returns true if every character in word is upper case, and false otherwise. You may use the
method Character.isUpperCase(char c) that determines whether char c is an upper
case character.
// method to see if a word is all upper case
private boolean isAllUpperCase(String word) {
boolean allSoFar = true; // all letters so
//far tested are upper case
for (int i = 0; i < word.length(); i++) {
if (Character.isUpperCase(word.charAt(i)) == false) {
allSoFar = false;
}
}
return allSoFar;
}
(5 marks)
CONTINUED
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CompSci 101 S2 C
SURNAME: ...................................................... FOR EN AMES: ...........................................................
Question 6 (10 marks)
a) What is the output when the following start()method is executed?
// mystery program
public void start() {
String s1 = "trial";
String s2 = "";
for (int i = 0; i<s1.length(); i++) {
char c = s1.charAt(i);
s2 = c + s2;
System.out.println(s2);
}
}
Show the output here:
t
rt
irt
airt
lairt
(5 marks)
b) What is the output when the following start()method is executed? Note that the helper
method printArray() just displays all of the elements of its parameter array on one line.
// mystery program
public void start() {
int[] numbers = {1,1,1,1,1};
printArray(numbers);
numbers = bump(numbers);
printArray(numbers);
numbers = bump(numbers);
printArray(numbers);
}
// helper method to print an array of ints on one line
private void printArray(int[] a) {
for (int j=0; j<a.length; j++) {
System.out.print(" " + a[j]);
}
System.out.println();
}
CONTINUED
Question/Answ er Sheet
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CompSci 101 S2 C
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// method to do something with an array of int numbers
private int[] bump(int[] nums) {
int[] value = new int[nums.length];
for (int j=0; j<nums.length; j++) {
value[j] = nums[j] + j;
}
return value;
}
Show the output here:
11111
12345
13579
(5 marks)
CONTINUED
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CompSci 101 S2 C
SURNAME: ...................................................... FOR EN AMES: ...........................................................
ROUGH WORKING (WILL NOT BE MARKED)
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CONTINUED
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CompSci 101 S2 C
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ROUGH WORKING (WILL NOT BE MARKED)
(You may detach this page from the answer booklet and use it for rough working)