int
for (i=5;i<=25;i=i+3) ;
Sopln(i)
{
Answers
Explanation:
Convert each of the following while-loops to a for-loop.
int num = 0;
while (num < 12)
{
if (num % 2 == 0)
System.out.println(num);
num++;
}
ANSWER:
int num;
for (num = 0; num < 12; num++) // or for (int num = 0; num < 12; num++)
{
if (num % 2 == 0)
System.out.println(num);
}
int num = 20;
int i = 1;
while (num < 35 && num > 5)
{
if (i % 2 == 0)
num += 2 * i;
else
num -= 3 * i;
System.out.println(i + ", " + num);
i++;
}
ANSWER:
int num = 20;
for (int i = 1; num < 35 && num > 5; i++)
{
if (i % 2 == 0)
num += 2 * i;
else
num -= 3 * i;
System.out.println(i + ", " + num);
}
// or another way, with multiple initialization
for (int num = 20, i = 1; num < 35 && num > 5; i++)
{
if (i % 2 == 0)
num += 2 * i;
else
num -= 3 * i;
System.out.println(i + ", " + num);
}
What is the output of each of the following code segments?
for (int i = 0; i < 50; i = i + 5)
{
if ( (i * 2) % 4 == 0)
System.out.println(i);
}
ANSWER:
0
10
20
30
40
for (int i = 0; i < 3; i++)
for (int j = 0; j < 2; j++)
System.out.println("i = " + i + ", j = " + j);
ANSWER:
i = 0, j = 0
i = 0, j = 1
i = 1, j = 0
i = 1, j = 1
i = 2, j = 0
i = 2, j = 1
for (int i = 0; i < 3; i++)
{
System.out.println("i = " + i);
for (int j = 0; j < 2; j++)
System.out.println(" j = " + j);
}
ANSWER:
i = 0
j = 0
j = 1
i = 1
j = 0
j = 1
i = 2
j = 0
j = 1
sum = 0;
for (int i = 0; i <= 3; i++)
for (int j = 5; j > i; j--)
sum += j;
System.out.println(sum);
ANSWER:
50
because the execution proceeds in the following way:
i j sum
0 5 5
0 4 9
0 3 12
0 2 14
0 1 15
1 5 20
1 4 24
1 3 27
1 2 29
2 5 34
2 4 38
2 3 41
3 5 46
3 4 50
What does the method mys return when called with an argument of 6? Choose one that applies.
public static int mys(int n)
{
int k = n;
int s = 1;
while (k > 1)
s *= k--;
return s;
}
121
520
720
5043
ANSWER: c (720 because k--; returns the value before the decrement, thus 6 * 5 * 4 * 3 * 2 = 720)
Write a program to print all of the capital letters in a line of input. For example, here is the sample session of the program.
Enter a line of input: This is the End of CSC 211
TECSC
ANSWER:
import java.util.Scanner;
public class PrintCaps
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.print("Enter a line of input: ");
String input = sc.nextLine(); // receive a whole line
for (int i = 0; i < input.length(); i++)
if (Character.isUpperCase(input.charAt(i)))
System.out.print(input.charAt(i)); // print one char at a time
System.out.println(); // to bring the cursor back
}
}
Write a program to print n lines of output, where the ith line of output consists of i asterisks. For example:
Enter a positive integer: 8
*
**
***
****
*****
******
*******
********
ANSWER: This is an interesting application which uses a nested loop.
import java.util.Scanner;
public class PrintAsterisks
{
public static void main(String[] args)
{
Scanner sc = new Scanner(System.in);
System.out.print("Enter a positive integer: ");
int num = sc.nextInt();
// The outer-loop for rows. Conceptually easier to start index (i) from 1.
for (int i = 1; i <= num; i++)
{
// i is the number of asterisks to print.
// Use an inner loop to print that many asterisks.
// The index (j) can start from 0 and goes until (and not including) i.
for (int j = 0; j < i; j++)
System.out.print('*'); // print one asterisk
System.out.println(); // to bring the cursor back
}
}
}