CSE110 Lab 4 Solved

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:
// FILENAME:
// SPECIFICATION:
while and for loops.
//
from 1 to n.
//
// LAB LETTER:
//-------------------------------------------------------------------------*/

(Put your name here)
Lab4.java
This program is for practicing the switch statement, do-while,

Using a while loop calculate the sum of integers

       Using a for loop find the factorial of n.
(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 <choice>

  //–>

• //  Create a switch statement with <choice> 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 <num> //–>
// Define 2 integer variables <sum> and <count> and

initialize them to 0

from 1 to n

//–>

• //  Use a while loop to calculate the sum of numbers
• //  Add the while-statement with the condition that

<count> variable is less than <num>

<num> ' is ' <sum>

while​(c​ ount​?​num​){
// increment <count> variable;
count​++;
// Calculate the <sum> by adding <count> to <sum> sum​ = ​sum​ + ​count​;

}

• //  Print the answer saying, ‘Sum of numbers from 1 – ‘ //–>
• //  exit from the switch with a break statement, what

happens if you don't use one?

break​;

<num> <num>

// case FACTORIAL: //–>
case​ ​???​:

initialize it to 1

initialize it to <num>,

// Ask the user to enter a number,

System.​out​.print(​”\nPlease enter a number n: “)​ ;
// Take user input and put it into the variable <num> //–>
// Compute the factorial of <num>
// Declare an long (integer) variable <fact> and

//–>

• //  Use a for loop to calculate the factorial of n
• //  Write a for loop with an integer variable <i> and

         //  condition that <i> greater than 1, increment <i> by 1
  

  for​(​int​ ​i​= n​ um​; ​i​ > 1 ; ​i​–){
  // write the expression <fact> = <fact> * <i> //–>

  }

         //Print the answer saying,'Factorial of' <num> 'is' <fact>
         //-->
  

• //  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 <num> //–>
  // 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' <num> 'are'
  

                          // if(num%i) == 0, then I is a factor (Here we check if
the number <num> is divisible by i)

Have a good day!'

again’

             // Print the numbers with two spaces

case​ QUIT: //–>

• //  Print ‘Your choice was <QUIT>, Quitting the program,

  //–>

• //  exit from the switch with a break statement //–>

// default:

default​:
// Print ‘Incorrect choice, ‘ <choice> ‘ Please choose

//–>
// Close the switch statement

//–>

//Close the do-while loop with a condition <choice> is not equal to

<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

} }​while​(choice!=QUIT);

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 <QUIT>, Quitting the program, Have a good day!