Questions for Discussion Week 4
Question 1:
Look at the following code segment and predict which if-else statements will run
successfully (and print output) and which will give run-time errors.
String s1 = null, s2 = "abc";
if (s2.charAt(0) == 'a' || s1.charAt(0) == 'a') // if statement 1
System.out.println("OR 1 True");
else
System.out.println("OR 1 False");
if (s2.charAt(0) == 'b' || s1.charAt(0) == 'a') // if statement 2
System.out.println("OR 2 True");
else
System.out.println("OR 2 False");
if (s2.charAt(0) == 'b' && s1.charAt(0) == 'b') // if statement 3
System.out.println("AND 1 True");
else
System.out.println("AND 1 False");
if (s2.charAt(0) == 'a' && s1.charAt(0) == 'a') // if statement 4
System.out.println("AND 2 True");
else
System.out.println("AND 2 False");
1
Question 2
Predict the output of the following code segment. Can you explain why?
double s = 0.0, t;
int count = 25;
while(count >0)
{
s += 0.1; // in this loop 0.1 is added to s 25 times.
count--;
}
//What is the value of s at this point of the program?
t = 2.5;
//Comparison block
if (s == t)
{
System.out.println("s is equal to t");
}
else
{
System.out.println("s is not equal to t");
}
Question 3:
Which of the following Boolean expressions is equivalent to this Boolean expression?
!(x < 0 && y < 0)
A.
!(x < 0) && !(y < 0)
B.
!(x >= 0) || !(y >= 0)
C.
x >= 0 && y >= 0
D.
x > 0 && y > 0
E.
x >= 0 || y >= 0
2
Question 4:
It is a boring Monday again, you are wondering when is Saturday again; hence you
decide to write a program to calculate the date of the Saturday.
Given a date X1 of a Monday in 2008, calculate what the date X2 of the Saturday in that
week is.
Input:
The date X1 in the form of <day month>. You may assume the date X1 is always a legal
date in 2008.
Output:
The date X2 in the form of <day month>. You may assume the date X2 is in 2008.
Sample run #1:
Enter date of Monday in <day month>: 25 8
The date of Saturday in that week is 30 8
Sample run #2:
Enter date of Monday in <day month>: 29 9
The date of Saturday in that week is 4 10
3
Question 5:
Consider the following code fragment that reads a student’s CAP and computes the
ranking for his honours degree.
public class ProcessCAP {
public static void main(String[] args) {
double i;
Scanner sc = new Scanner(System.in);
i = sc.nextDouble();
if (i>=4.5) System.out.println("First class");
if (i>=4.0 && i<=4.5) System.out.println("Second upper");
if (i>=3.5) System.out.println("Second lower");
}
}
a.
b.
What is the output of the program if:
 i = 4.8?
 i = 4.5?
 i = 3.0?
Any suggestions to make the program more robust?
Question 6:
Write a program that will take in a string (of length no longer than ten) and determine if
the string is palindrome or not. A palindrome is a (see http://www.palindrome.com).
We will consider the simplest palindromes where there is no space character in it.
Examples of palindrome: “DAD”, “MADAM”, “RACECAR”.
4