CS110 Programming Language I. Lab 3: Java basics II (model answer) Dr. Hadil Shaiba

Transcription

1 CS110 Programming Language I Lab 3: Java basics II (model answer) Dr. Hadil Shaiba Computer Science Department Spring 2017

2 Lab Objectives: In this lab, the student will practice: Defining variables of different data types Reading data values from the user. Compiling and executing Java applications. Writing and evaluating mathematical expressions Lab Exercise 1: Problem Description Write a program that asks the user to input 2 numbers x and y, then swap the values of x and y. Sample output Please enter number 1: 2 Please enter number 2: 4 **Exchange Result ** Number1: 4 Number2: 2 Code Skelton // Program Title public class ExchangeNum { //declear variables //read numbers from users //do the SWAP and output the result } Page 2

3 // Lab Exercise 1: Lab3Q1.java // Reads two numbers from the user and exchanges their values then prints them out public class Lab3Q1 { // declear variables int number1,number2; int temp = 0; System.out.print("Please enter number 1: "); // prompt first number number1 = input.nextint(); // read first number System.out.print("Please enter number 2: "); // prompt second number number2 = input.nextint(); //read second number // exchange numbers temp = number1; number1 = number2; number2 = temp; // print the exchanged numbers System.out.println("**Exchange Result **"); System.out.println("Number1: " + number1); System.out.println("Number2: " + number2); } // end class Lab3Q1 Page 3

4 Follow-up Questions and Activities Modify the program to divide each number by 2 before printing the result. // Lab Exercise 1: Lab3Q1.java // Reads two numbers from the user and exchanges their values then prints them out public class Lab3Q1 { // declear variables int number1,number2; int temp = 0; System.out.print("Please enter number 1: "); // prompt first number number1 = input.nextint(); // read first number System.out.print("Please enter number 2: "); // prompt second number number2 = input.nextint(); //read second number // exchange numbers temp = number1; number1 = number2; number2 = temp; // print the divided numbers System.out.println("**Exchange Result **"); System.out.println("Number1: " + number1/2); System.out.println("Number2: " + number2/2); } // end class Lab3Q1 Page 4

5 Lab Exercise 2: Problem Description Write a program that reads in the currency in dollars and prints the currency in riyals. Use the bellow flowchart to write the program. Do all calculations in output statements START Input dollar riyal 3.75 x dollar Print riyal STOP Sample output Please enter the currency in dollars: 50 The currency in riyals is: Code Skelton // Program ToRiyal public class ToRiyal { //declear variable //declear constant //read currnecy from user //do the calcualtion and output the result } Page 5

6 // Lab Exercise 2: Lab3Q2.java // Reads a currency in dollars and prints the currency in riyals public class Lab3Q2 { // define variables double dollar; // define the constant value double c= 3.75; System.out.print("Please enter the currency in dollars: "); // prompt currency dollar = input.nextdouble(); // read currency System.out.println("The currency in riyals is: " + (c*dollar)); // calculate and prompt circle's area } // end class Lab3Q2 Page 6

7 Assignment Problem(s) Q1: Write a program that reads in the values x and y. Your program should compute the expression shown below and assign the result to the variable z. The program should finally print the mean of x, y, and z. Note: z=x+4y Sample output Please enter x: 10 Please enter y: 20 The value of z is: 90 The mean of x, y, and z is: 40 // Lab Exercise 2: Lab3Hw1.java The // Reads solution: the values x and y from the user and calculates z then prints the mean of x, y, and z public class Lab3Hw1 { // define variables int x, y, z; // calculate and prompt x and y System.out.print("Please enter x's value: "); // prompt x's value x = input.nextint(); // read x's value System.out.print("Please enter y's value: "); // prompt y's value y = input.nextint(); // read y's value z = x+(4*y); // calculate z's value System.out.println("The value of z is: "+ z); System.out.println("The mean of x, y, and z is: "+ ((x+y+z)/3)); } // end class Lab3Hw1 Page 7

8 Q2: Write a program that asks the user to type the price without tax of one kilogram of tomatoes, the number of kilograms you want to buy and the tax in percent units. The program must calculate the total price including taxes. Sample output Please enter the price without tax of one kilogram of tomatoes: 10 Please enter the number of kilograms: 5 Please enter tax in percent units: 3 Total price: 51.5 S.R. // Lab Exercise 2: Lab3Hw2.java // The Reads solution: the price of 1kg of tomatoes without tax and calculates the price of (n)kg of tomatoes with tax then prints the result public class Lab3Hw2 { double price, num_kg, total_price, tax; // define variables // prompt the price of 1kg of tomatoes without tax System.out.print("Please enter the price without tax of one kilogram of tomatoes: "); // read the price of 1kg of tomatoes without tax price = input.nextdouble(); // propt the required number of kilograms System.out.print("Please enter the number of kilograms: "); // read the number of kilograms num_kg = input.nextdouble(); // propt the tax in percent units System.out.print("Please enter tax in percent units: "); // read the tax in percent unit tax = input.nextdouble(); total_price = (price*num_kg)+ (price *num_kg*tax/100); // calculate the price with tax //print the price with tax System.out.println("\nTotal Price = "+ total_price +" S.R. "); Page 8 } // end class Lab3Hw2