2. What are the two main components to the CPU and what do each of them do? 3. What is the difference between a compiler and an interpreter?

Transcription

1 COSC 117 Exam 1 Key Spring 2011 Part 1: Definitions & Short Answer 1. What do CPU and ALU stand for? CPU Central Processing Unit ALU Arithmetic and Logic Unit 2. What are the two main components to the CPU and what do each of them do? The CPU consists of the ALU (Arithmetic and Logic Unit) and the Control Unit. The ALU does the calculations and the Control Unit controls the running of the program. 3. What is the difference between a compiler and an interpreter? A compiler will take a program written in a high-level language, translate it into machine language and then save the machine language program to a file that can be run on the computer. An interpreter does essentially the same thing except that it translates the high-level language to machine language one command at a time and does not save the machine language program to a file. 4. What are the four basic types of instructions and the two basic types of control instructions? 1. Assignment 2. Read 3. Write 4. Call to a procedure 5. Conditional statement 6. Loop 5. In object oriented programming, what are the states and what are the methods? States are the attributes of the object, data that the object stores, and methods are the actions you can do on the object.

2 Part 2: Program Traces 1. For each of the program inputs below write the output of the program. public class Exam1Trace1 { System.out.print("Input x: "); double x = keyboard.nextdouble(); System.out.print("Input y: "); int y = keyboard.nextint(); double z = 3*x-y/2; double w = Math.pow(x, y); System.out.println(x + " " + y + " " + z + " " + w); (a) Input x: 1.2 Input y: 2.5 RUN TIME ERROR (b) Input x: 5 Input y: (c) Input x: 4 Input y: (d) Input x: 3 Input y:

3 2. For each of the program inputs below write the output of the program. public class Exam1Trace2 { System.out.print("Input x: "); int x = keyboard.nextint(); System.out.print("Input y: "); int y = keyboard.nextint(); (a) (b) (c) (d) (e) if (x-y < 0){ System.out.println(y + " is larger than " + x); else if (x+y > 10){ System.out.println((x+y) + " is greater than 10"); else if (y > 0){ System.out.println(y + " is positive"); else if (x < 0){ System.out.println(x + " is negative"); else { System.out.println("None of the above. "); Input x: -6 Input y: 6 6 is larger than -6 Input x: 5 Input y: 2 2 is positive Input x: -1 Input y: -2-1 is negative Input x: 25 Input y: is greater than 10 Input x: 7 Input y: -7 None of the above.

4 3. For each of the program inputs below write the output of the program. public class Exam1Trace3 { System.out.print("Input n: "); int n = keyboard.nextint(); (a) (b) (c) (d) (e) while (n > 0){ if (n % 3 == 0){ n = n/3; else if (n % 10 == 0){ n += 2; else if (n % 2 == 0){ n = n/2; else { n--; System.out.print(n + " "); Input n: Input n: Input n: Input n: Input n:

5 4. The following is an Alice program that has two objects in the world, Socrates and a Snowman. There are also two numeric variables n and ThingNumber. If the user inputs the numbers 1 then 2 then 5 then 0 what will the program display? Be explicit on what things happen together and what happens in order. world.my first method ( ) ThingNumber = 1, n = 1 Do in order While ( ThingNumber > 0 ) ThingNumber set value to ( ask user for a number question = Enter a Number: ) If ( ThingNumber < 2 ) Else Do together Do in order socrates move left 0.5 meters socrates move right 0.5 meters Do in order snowman resize 2 snowman resize 0.5 n set value to ThingNumber While ( n > 0 ) Do together snowman turn left 1 revolution socrates turn right 1 revolution decrement n by 1 Input 1: Socrates moves to the left ½ meter and at the same time the Snowman increases in size by a factor of 2. Then Socrates moves to the right ½ meter and at the same time the Snowman returns to his normal size. Input 2: Socrates and the Snowman rotate in opposite directions twice and they rotate at the same time. Input 5: Socrates and the Snowman rotate in opposite directions five times and they rotate at the same time. Input 0:Socrates moves to the left ½ meter and at the same time the Snowman increases in size by a factor of 2. Then Socrates moves to the right ½ meter and at the same time the Snowman returns to his normal size. Then the program ends.

6 Part 3: Coding 1. Write a program that will ask the user to input their first name, last name, and year they graduated from high school or will graduate from high school(in yyyy format, such as 1985 or 2015). The program should calculate their age (assuming that they graduate from high school at age 18) and then print out the users name in familiar form (like John Doe) followed by their age. Then if the user's age is less than or equal to 12 print out You have a long way to go., if the user's age is greater than 12 but less than 16 then print out You have a bit further to go., if the user's age is greater than or equal to 16 but less than 18 then print out You are almost done., if the user is 18 print out You graduate this year. and finally if the user's age is greater than 18 print out You are already done with high school.. public class Exam1Prog1b { System.out.print("Input First Name: "); String first = keyboard.next(); System.out.print("Input Last Name: "); String last = keyboard.next(); System.out.print("Input Year of High School Graduation (yyyy): "); int year = keyboard.nextint(); int age = year + 18; System.out.println(first + " " + last + " Age: " + age); if (age <= 12){ System.out.println("You have a long way to go."); else if (age < 16) { System.out.println("You have a bit further to go."); else if (age < 18) { System.out.println("You are almost done."); else if (age == 18) { System.out.println("You graduate this year."); else { System.out.println("You are already done with high school.");

7 2. Write a program that will take as input a positive integer n from the user, that is, the input could be 1 or 2 or 3 etc.. The program should calculate and output the sum of all the numbers from 1 to n, the sum of all the squares of the numbers from 1 to n and the sum of all the cubes of the numbers from 1 to n. That is, n, n 2 and n 3. The program should continually ask the user for another number until the user inputs -1. public class Exam1Prog2b { System.out.print("Input a number: "); int n = keyboard.nextint(); while (n!= -1){ int sum = 0; int sumsquare = 0; int sumcube = 0; int count = 1; while (count <= n){ sum = sum + count; sumsquare = sumsquare + count*count; sumcube = sumcube + count*count*count; count++; System.out.println("Sum = " + sum); System.out.println("Sum Squares = " + sumsquare); System.out.println("Sum Cubes = " + sumcube); System.out.print("Input a number: "); n = keyboard.nextint();

8 3. Write a program that will take an input of a positive integer number from the user, say n. Repeat the following process until n is less than equal to 5. If n is divisible by 3 (that is, the remainder when you divide the number by 3 is 0) replace n by n/3 otherwise replace n by 2n 1. The program must print out the sequence along with a count of the number of numbers in the sequence. public class NiftySequence2 { System.out.print("Input a number: "); int n = keyboard.nextint(); System.out.print("Sequrence: " + n + " "); int count = 1; while (n > 5){ if (n % 3 == 0){ n = n/3; else{ n = 2*n-1; System.out.print(n + " "); count++; System.out.println(); System.out.println("The number of numbers in the sequence is " + count);