I. True/False: (2 points each)

Transcription

1 CS Introduction to Programming Midterm Exam #1 - Prof. Reed Fall 2004 What is your name?: (0 points) There are two sections: I. True/False points; ( 26 questions, 2 points each) II. Multiple Choice points; ( 12 questions, 4 points each) points total This test is worth 10% of your final grade. For all problems you must put your answers on the bubble form using a #2 pencil. This test is open book and open notes. You have 50 minutes. For the True/False questions, if the answer is True, fill in a on your answer form. If the answer is False, fill in b on your answer form. For the multiple choice problems, select the best answer for each one and select the appropriate letter on your answer sheet. Be careful - more than one answer may seem to be correct. Some questions are tricky. Several problems ask you to determine whether something is valid. Something is valid if it would not generate a compiler error and would execute without the program crashing. I. True/False: (2 points each) T F 1. Consider the three looping structures for, while, and do-while. Any one of them can be implemented using any one of the others, with the help of additional code. T F 2. In UNIX, the list command is used to get a directory listing. T F 3. The following statements displays three lines of output System.out.println("fir"); System.out.print("st "); System.out.println("sec"); System.out.println("ond"); T F 4. Comments on a single line can be indicated as follows: /*...comment here... */ T F 5. In BlueJ it is not necessary to have the method public static void main (String[] args) to run a program. T F 6. A single class Employee can be used to make as many instances of Employee as you want. T F 7. Any program that can be written with if - else statements can be rewritten without the else statements. T F 8. A method that does not return any value must have a return type of void. T F 9. Typically a class you create will have get and set methods for its private instance variables. T F 10. It is considered good programming style to declare instance variables as public as it makes programs much easier to write. T F 11. Methods of class Employee (that we saw during class) have an implicit parameter called this. CS Intro. to Programming, Midterm Exam #1, page 1 of 9

2 T F 12. A static method cannot acces a private instance variable. T F 13. Within a class it is acceptable to have multiple methods with the same method name. T F 14. The following code is valid (compiles and runs) in Java: for(int z=0; ;z++ ) z--; T F 15. The output of the statement below is: 1 System.out.println( 5 % 2); T F 16. The output of the statement below is: 1 System.out.println( 3 % 7); T F 17. The output of the statement below is: 1 System.out.println( 6 % -5); T F 18. To check if an integer value is between 3 and 5, we could use the following: int x = 4; if( (x >= 3) && ( x =< 5) ) System.out.println("It is between 3 and 5"); T F 19. The output of the program segment below is the text: False boolean x = false; if ( x = true) System.out.println("False"); else System.out.println("True"); T F 20. The output of the program segment below is the text: Yes boolean x = true; if ( x) System.out.print("Yes"); else System.out.print("No"); System.out.print(" *** "); CS Intro. to Programming, Midterm Exam #1, page 2 of 9

3 T F 21. The output of the program segment below is the text: not rich Done int hourlywage = 6; if ( hourlywage >= 9) if ( hourlywage >= 5) System.out.print("middle class"); else System.out.print("not rich"); System.out.println(" Done"); T F 22. The following code will give the output: Value is: 120 int x = 5; for (int i=x; i>0; i--) x = x * i; System.out.println("Value is: " + x); For the next 4 questions, select T if it is a valid identifier, otherwise select F. An identifier is valid if it could be used as a variable name or a method name. T F 23. AVeryLongVariableNameCouldBeAPainToTypeEveryTime T F 24. ALLUPPERCASE T F 25. 2goodToBeTrue T F 26. astounding! CS Intro. to Programming, Midterm Exam #1, page 3 of 9

4 II. Multiple Choice (4 pts. each) 27. Consider the following segment of code: int number = 125 % 25; System.out.println("The answer is: " + number); What is the output? a) The answer is: 5 b) The answer is: 0 c) The answer is: 25 d) The answer is: Consider the program segment given below. Its output is: int i = 5; int j = 7; System.out.println("" + i + j + " is the answer"); a) is the answer b) 12 is the answer c) 57 is the answer d) 5 7 is the answer 29. Consider the program segment given below. Its output is: int i = 5; int j = 7; System.out.println(i + j + " is the answer"); a) is the answer b) 12 is the answer c) 57 is the answer d) 5 7 is the answer 30. Consider the program segment given below. Its output is: String s = "5"; int j = 7; System.out.println("" + Integer.parseInt(s) + j); a) is the answer b) 12 is the answer c) 57 is the answer d) 5 7 is the answer CS Intro. to Programming, Midterm Exam #1, page 4 of 9

5 31. Consider the method given below. It can best be described as a method that: public boolean methodaa( int number) if ( (number==1) (number==2) ) return true; for (int i=2; i < number/2; i++) if ( number%i == 0) return false; return true; a) checks to see if a number is prime b) checks to see if a number is even c) checks to see if a number is odd d) does not compile 32. Consider the method given below. If its output is: How was the method called? public void methodb(int r, int k, int n) int i, j; for( j=k; j<=n; j++) for( i=1; i<=r; i++) System.out.print(" " + i*j); System.out.println(); a) methodb(3, 3, 1); b) methodb(4, 1, 3); c) methodb(3, 6, 3); d) methodb(4, 6, 3); CS Intro. to Programming, Midterm Exam #1, page 5 of 9

6 33. Consider the method given below. For a parameter value of its return value is: public int methodab( int number) int x = number; int y = 0; while ( x > 0) y = y * 10 + x%10; x = x / 10; return y; a) 2 b) c) 1357 d) Consider the method given below. Its output is: public void methoda() int x = 13572; while (x > 10) x = x / 10; System.out.print("" + x ); a) 2 b) c) 1357 d) 1 CS Intro. to Programming, Midterm Exam #1, page 6 of 9

7 35. Consider the class given below, along with the driver class for it. You may assume each of these classes is stored in a separate file: This class: class ClassA private int x = 1; public ClassA( int x) this.x = x; class ClassADriver public static void main(string[] args) ClassA instance1 = new ClassA( 5); a) compiles and runs, creating an instance of ClassA and setting the value of field x to 5. b) compiles and runs, creating an instance of ClassA with the default value for x = 1 c) compiles but generates an error when run d) doesn t compile 36. What happens if everything stays as in the previous problem, except the code in main becomes: // class ClassA same as before class ClassADriver public static void main(string[] args) ClassA instance1 = new ClassA(); This program: a) compiles and runs, creating an instance of ClassA and setting the value of field x to 5. b) compiles and runs, creating an instance of ClassA with a default value for x = 1 c) compiles but generates an error when run d) doesn t compile CS Intro. to Programming, Midterm Exam #1, page 7 of 9

8 37. Consider the class given below, along with the driver class for it. You may assume each of these classes is stored in a separate file: class ClassB private int x=0; public ClassB( ) this( 1); public ClassB( int x) this.x = x; class ClassBDriver public static void main(string[] args) ClassB instance1 = new ClassB( ); This program: a) compiles and runs, creating an instance of ClassB and setting the value of field x to 1. b) compiles and runs, creating an instance of ClassB with the default value for x = 0 c) compiles but generates an error when run d) doesn t compile CS Intro. to Programming, Midterm Exam #1, page 8 of 9

9 38. What is the output of the code given in the two columns below when method startup() is called? class Confuse private int x; private int y; public Confuse() x = 1; y = 3; private void first(int x, int y) x = 4; y = 3; private void second(int y) x = x + 1; y = 4; private void setxy( int x, int y) this.x = x; this.y = y; second( this.y); private void display() System.out.println(x + " " + y); public void startup() first( x, y); second( x); third( x, y); display(); private void third(int s, int t) setxy( s, t); s = 3; t = 1; a) 3 2 b) 1 3 c) 5 4 d) 4 6 CS Intro. to Programming, Midterm Exam #1, page 9 of 9