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CS110D Programming Language I Lab8 : More Loops (model answer) Computer Science Department Fall 2016 Lab Objectives: After finishing this lab, the students will practice: Using different looping mechanisms. Using continue and break statements. Using nested control structures. Lab Exercise 1: Problem Description For the given program segments, read the code and write the expected output in the space provided below. [Note: Do not execute these statements on a computer.] Program Segment for (int i = 0; i <= 12; i++) { if (i % 2 == 0) { continue; } if (i == 7) { break; } System.out.printf("%d \n", i); } Answer Page|2 Program Segment for (int i = 1; i <= 3; i++) { for (int j = 1; j <= 5; j++) { System.out.printf("%4d", i*j); } System.out.println(); } Answer Program Segment Int num = 4; do { System.out.println(num); num+=4; } while (num <= 20) Answer Page|3 Lab Exercise 2: Problem Description The process of finding the largest value (i.e., the maximum of a group of values) is used frequently in computer applications. For example, a program that determines the winner of a sales contest would input the number of units sold by each salesperson. The salesperson who sells the most units wins the contest. Use a do..while loop to write a java application that inputs a series of 10 integers then determines and prints the largest integer. Your program should use at least the following three variables: A) Counter: A counter to count to 10 (i.e., to keep track of how many numbers have been input and to determine when all 10 numbers have been processed). B) Number: The integer most recently input by the user. C) Largest: The largest number found so far. Sample output Enter number: 56 Enter number: -10 Enter number: 200 Enter number: 25 Enter number: 8 Enter number: 500 Enter number: -20 Enter number: 678 Enter number: 345 Enter number: 45 The Largest Number is 678 Code import java.util.Scanner; public class LargestNum{ public static void main(String[] args){ Scanner input = new Scanner(System.in); int number, count = 0; int largest = -100000000; do { System.out.println("Enter number: "); number = input.nextInt(); if (number > largest){ largest = number; } count++; } while (count<10); System.out.println("Largest number is " + largest); } } Page|4 Follow-up Questions and Activities Modify the code to allow the user to enter unknown number of integers that ends with -9999 as sentinel value. Code import java.util.Scanner; public class LargestNum{ public static void main(String[] args){ Scanner input = new Scanner(System.in); int number; int largest = -100000000; do { System.out.println("Enter number or -9999 to exit: "); number = input.nextInt(); if (number == -9999){ break; } if (number > largest){ largest = number; } } while (true); System.out.println("Largest number is " + largest); } } Page|5 Assignment Problem(s) Question 1 Write a java program that asks the user to input the length and width of a rectangle. Then it should draw this rectangle on the screen using stars. [Hint: Use a for loop] Sample output Code import java.util.Scanner; public class RegtanglePrint{ public static void main(String[] args){ Scanner input = new Scanner(System.in); int length, width; System.out.print("Enter the length of the rectangle: "); length = input.nextInt(); System.out.print("Enter the width of the rectangle: "); width = input.nextInt(); for (int i = 0; i < width; i++) { for (int j = 0; j < length; j++) { System.out.print(" * "); } System.out.println(); } } } Page|6 Question 2 Use a do..while loop to write a java program that asks the user to input a sequence of integers. Then it should find and display each of the following: a) b) c) d) Number of integers. Sum of integers. Number of odd integers. Number of even integers. [Hint: Use (-9999) as a sentinel value to end the sequence and skip an endless loop] Code import java.util.Scanner; public class NumSummary{ public static void main(String[] args){ Scanner input = new Scanner(System.in); int number, odd = 0, even = 0, sum = 0, count = 0; do { System.out.println("Enter number or -9999 to stop: "); number = input.nextInt(); if (number == -9999) break; if (number % 2 == 0) even++; else odd++; sum += number; count++; } while (true); System.out.println("Number System.out.println("Sum of System.out.println("Number System.out.println("Number of integers is " + count); integers is " + sum); of odd integers is " + odd); of even integers is " + even); } } Page|7