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CSE110 - Principles of Programming with Java - 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: (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 <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
//-->
// Use a while loop to calculate the sum of numbers
from 1 to n
// Add the while-statement with the condition that
<count> variable is less than <num>
while(count ?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 - ' <num> ' is ' <sum>
//-->
// 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 <num>
//-->
// Compute the factorial of <num>
// Declare an long (integer) variable <fact> and
initialize it to 1
//-->
// Use a for loop to calculate the factorial of n
// Write a for loop with an integer variable <i> and
initialize it to <num>,
// condition that <i> greater than 1, increment <i> by 1
for(int i= num; 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
<num>
// Hint: The loop should terminate after iterating upto
<num>
// 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)
// Print the numbers with two spaces
case QUIT:
//-->
// Print 'Your choice was <QUIT>, Quitting the program, Have a good day!'
//-->
// exit from the switch with a break statement //-->
// default: default:
// Print 'Incorrect choice, ' <choice> ' Please choose
again'
//-->
// Close the switch statement
//-->
//Close the do-while loop with a condition <choice> is not equal to <QUIT>
}
}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 <QUIT>, Quitting the program, Have a good day!
