CSE 114 Midterm Exam I Fall 2010 Group A 1

Transcription

1 CSE 114 Midterm I Fall 2010 Group A Name: First Last Student ID # Please leave at least one seat between yourself and the person next to you. No books, notes, or electronic equipment can be used during the exam. Put a box around all answers. Any CHEATING will result in an F as well as being written-up on academic dishonesty. Question # Points Available Total: 100 Points Earned ATTENTION: Make sure your exam has 9 pages and all 20 questions. CSE 114 Midterm Exam I Fall 2010 Group A 1

2 Question 1 (5 Points) Make the following conversions between number systems: a) 73 from decimal to binary b) 44 from decimal to hexadecimal c) from binary to hexadecimal d) from binary to decimal e) e29 from hexadecimal to decimal Question 2 (5 Points) This semester we have started out writing code using the Sparky server. a) When connecting to Sparky via SSH, what secure port number do we use? b) What operating system does Sparky use? c) What command should you use to specify permissions on all of your work so that other Sparky users may not access your files? d) What command would you use on Sparky to change the present working directory to the pwd s parent directory (one level up)? e) What file extension is used for all java source code files? Question 3 (5 Points) What company has been the caretaker of the Java programming language since purchasing Sun Microsystems in April of 2009? CSE 114 Midterm Exam I Fall 2010 Group A 2

3 Question 4 (5 Points) String s = "HELLO"; int i = 0; while (s.length() < 10) s += s.substring(i, i+2); i++; System.out.println(s); Question 5 (5 Points) int count = 0; for (int i = 0; i < 4; i++) int j = 0; while (j < 5) if ((j % 2) == 0) count++; j++; System.out.println(count); Question 6 (5 Points) The Math.random() method returns a random double in the range of 0.0 up to but not including 1.0 (think of it as 0.0 to ). Use this method to initialize the randomlowercaseletter variable below such that it assigns it a random lower-case letter ( a z ). Note that all letters in that range should be equally likely to be selected. Note that you may not use iteration for this question. Recall that the ASCII value of a is 97, and of z is 122. char randomlowercaseletter = CSE 114 Midterm Exam I Fall 2010 Group A 3

4 Question 7 (5 Points) The dummy method below compiles without error. When called, how much memory will be allocated on the call stack for all variables local to this method? public static void dummy( String a, int b) double c = b * 5; double d = c * 5; System.out.print(a); System.out.print(c); System.out.print(d); Question 8 (5 Points) The CBV program below compiles without error. What results from executing this program? public class CBV public static void main(string[] args) String str = "XYZ"; int i = 789; reset(str, i); System.out.println(str); System.out.println(i); public static void reset( String a, int b) a = "A"; b = 0; Question 9 (5 Points) The code below compiles without error. What output results from running it? int x = 5; int y = x/2; int z = y * 20; x = z/x; System.out.println(x); CSE 114 Midterm Exam I Fall 2010 Group A 4

5 Question 10 (5 Points) The whatisthis method below compiles and executes without error. What output would result from calling : a) whatisthis(20); b) whatisthis(10); c) whatisthis(5); d) whatisthis(2); e) whatisthis(-5); public static void whatisthis(int x) if (x < 0) System.out.println("A"); else if (x < 10) if (x > 6) System.out.println("B"); else if (x > 3) System.out.println("C"); else System.out.println("D"); else System.out.println("E"); Question 11 (5 Points) String s1 = new String("XYZ"); String s2 = new String("XYZ"); if (s1 == s2) System.out.println("A"); else if (s1.equals(s2)) System.out.println("B"); else System.out.println("C"); CSE 114 Midterm Exam I Fall 2010 Group A 5

6 Question 12 (5 Points) public class Stat static int a; static String b; public static void main(string[] args) a = 5; b = "ABC"; method1(a); System.out.println(a); System.out.println(b); a = 5; b = "ABC"; method2(b); System.out.println(a); System.out.println(b); b = "ABC"; method3(b); System.out.println(b); public static void method1(int x) x = 0; b = "DEF"; public static void method2(string y) a = 0; y = "DEF"; public static void method3(string z) z.substring(1); CSE 114 Midterm Exam I Fall 2010 Group A 6

7 Question 13 (5 Points) public class Ret static int a; public static void main(string[] args) a = 99; int num = geta(); num = 20; System.out.println(a); public static int geta() return a; Question 14 (5 Points) public class LogicalOps public static void main(string[] args) foo("alphab"); foo("betaa"); foo("alphab"); foo("betaa"); foo("alphab"); public static void foo(string text) if ((text.indexof('a')!= -1) && ((text.charat(0) == 'b') (text.charat(0) == 'B'))) System.out.println("true"); else System.out.println("false"); CSE 114 Midterm Exam I Fall 2010 Group A 7

8 Question 15 (5 Points) In HW 2 we manipulated IP addresses using the Ipv4 standard. Provide an example of such an address: Question 16 (5 Points) int v = 1; int w = 2; int x = 3; int y = 4; int z = 5; v = w; v += 1; w = x; w += 2; x = y; x += 3; y = z; y += 4; z = v; z += 5; System.out.println(v); System.out.println(w); System.out.println(x); System.out.println(y); System.out.println(z); Question 17 (5 Points) String str = "a\tb\"c\nd"; int numchars = str.length(); System.out.println(numChars); CSE 114 Midterm Exam I Fall 2010 Group A 8

9 Question 18 (5 Points) What is approximately the largest positive number that can be fit into Java s int data type. Note, don t give an answer in powers of 2, express your answer using the decimal number system. Question 19 (5 Points) int x = 51; int y = 7; int z = x % y; System.out.println(z); Question 20 (5 Points) Examine the testwhile and testdowhile methods below and you ll see that they return similar values for some, but not all x input argument values. What is the largest input value for x that would produce different results for these two methods? public static int testwhile(int x) int num = 1; int i = 5; while (i < x) num *= i; i++; return num; public static int testdowhile(int x) int num = 1; int i = 5; do num *= i; i++; while (i < x); return num; CSE 114 Midterm Exam I Fall 2010 Group A 9