CSE 110 – Lab 4

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This lab is for practicing the switch statement, do-while, while and for loops.
Use the following Coding Guidelines:
• When declaring a variable, you usually want to initialize it.
• Use white space to make your program more readable.
• Use comments after the ending brace of classes, methods, and blocks to identify to which block it
belongs.
Assignments Documentation:
At the beginning of each programming assignment you must have a comment block with the
following information:
/*—————————————————————————
// AUTHOR: (Put your name here)
// FILENAME: Lab4.java
// SPECIFICATION: This program is for practicing the switch statement, do-while,
while and for loops.
// Using a while loop calculate the sum of integers
from 1 to n.
// Using a for loop find the factorial of n.
// LAB LETTER: (Put your Lab Letter here)
//————————————————————————-*/
Getting Started
Create a class called Lab4. Use the same setup for setting up your class and main method as you did
for the previous assignments. Be sure to name your file Lab4.java.
Hints
Please replace //–> with the correct program to finish the task according to the corresponding
comment.
Please replace ??? with the correct program to enable the program to run as required.
// Import required java utility Scanner package
import java.util.Scanner;
// Declare class (Lab4)
public class Lab4
{
// Write the main method
public static void main(String[] args)
{
// Declare Constant integers SUM = 1, FACTORIAL = 2, FACTORS = 3, QUIT = 4.
final int SUM= 1;
final int FACTORIAL = 2;
//–>
// Create an integer variable named choice.
//–>
// Create a Scanner object (you may need to import the class)
//–>
// Create a do-while loop that exits only when the user chooses quit
(choice = QUIT)
// Have the do-statement here
???{
// Print the following options:
// “This program does the following:”
//–>
// “1. Sum of numbers from 1 to n”
//–>
// “2. Factorial of n”
//
// “3. Factors of n”
//–>
// “4. Quit”
//–>
// “Please choose an option ”
//–>
// Read the value the user enters and store it in an integer
variable
//–>
// Create a switch statement with as input for the 3 cases
switch(???) {
// case SUM:
case SUM:
// Ask the user to enter a number,
System.out.print(“\nPlease enter a number n: “);
// Take user input and put it into the variable
//–>
// Define 2 integer variables and and
initialize them to 0
//–>
// Use a while loop to calculate the sum of numbers
from 1 to n
// Add the while-statement with the condition that
variable is less than
while(count?num){
// increment variable;
count++;
// Calculate the by adding to
sum = sum + count;
}
// Print the answer saying, ‘Sum of numbers from 1 – ‘
‘ is ‘
//–>
// exit from the switch with a break statement, what
happens if you don’t use one?
break;
// case FACTORIAL:
//–>
case ???:
// Ask the user to enter a number,
System.out.print(“\nPlease enter a number n: “);
// Take user input and put it into the variable
//–>
// Compute the factorial of
// Declare an long (integer) variable and
initialize it to 1
//–>
// Use a for loop to calculate the factorial of n
// Write a for loop with an integer variable and
initialize it to ,
// condition that greater than 1, increment by 1
for(int i= num; i > 1 ; i–){
// write the expression = *
//–>
}
//Print the answer saying,’Factorial of’ ‘is’
//–>
// exit from the switch with a break statement.
//—>
case FACTORS:
// Ask the user to enter a number,
System.out.print(“\nPlease enter a number n: “);
// Take user input and put it into the variable
//–>
// Write a loop to find which numbers are the factors of

// Hint: The loop should terminate after iterating upto

// Print the a statement saying,’Factors of’ ‘are’
// if(num%i) == 0, then I is a factor (Here we check if
the number is divisible by i)
// Print the numbers with two spaces
case QUIT:
//–>
// Print ‘Your choice was , Quitting the program,
Have a good day!’
//–>
// exit from the switch with a break statement
//–>
// default:
default:
// Print ‘Incorrect choice, ‘ ‘ Please choose
again’
//–>
// Close the switch statement
//–>
//Close the do-while loop with a condition is not equal to

}
}while(choice!=QUIT);
}
}
SAMPLE INPUT:
1
10
2
20
3
65
8
4
SAMPLE OUTPUT:
This program does the following:
1. Sum of numbers from 1 to n
2. Factorial of n
3. Factors of n
4. Quit
Please choose an option
Please enter an integer n:
Sum of numbers from 1 – 10 is 55
This program does the following:
1. Sum of numbers from 1 to n
2. Factorial of n
3. Factors of n
4. Quit
Please choose an option
Please enter an integer n:
Factorial of number 20 is 21c3677c82b40000
This program does the following:
1. Sum of numbers from 1 to n
2. Factorial of n
3. Factors of n
4. Quit
Please choose an option
Please enter an integer n:
Factors of number 65 are
1 5 13 65
This program does the following:
1. Sum of numbers from 1 to n
2. Factorial of n
3. Factors of n
4. Quit
Please choose an option
Incorrect choice, 8 Please choose again
This program does the following:
1. Sum of numbers from 1 to n
2. Factorial of n
3. Factors of n
4. Quit
Please choose an option
Your choice was , Quitting the program, Have a good day!