Spring Semester 09 Exam #2 Dr. Dillon. (04/02)

Transcription

1 Spring Semester 09 Exam #2 Dr. Dillon. (04/02) Form 1 A Last name (printed): First name (printed): Directions: a) DO NOT OPEN YOUR EXAM BOOKLET UNTIL YOU HAVE BEEN TOLD TO BEGIN. b) You have 80 minutes to complete the exam (12:40 2:00 pm) c) This exam booklet contains 26 multiple choice questions, each weighted equally (5 points) and one 20 point programming problem. (27 questions, 10 total pages) d) You may also use one 8.5" x 11" note sheet during the exam. No other reference materials or calculating devices may be used during the examination. e) Questions will not be interpreted during the examination. f) You should choose the single best alternative for each question, even if you believe that a question has multiple correct answers, is ambiguous or contains a typographic error. g) Fill in the requested information at the top of this exam booklet. h) Use a #2 pencil to encode information on the OMR form. i) Encode the following on the OMR form: Last name and first initial MSU PID Exam form (see the top right corner of this page) j) Sign the OMR form. k) Only answers recorded on your OMR form will be counted for credit for multiple-choice questions. l) Completely erase any responses on the OMR form that you wish to delete. m) You must turn in this exam booklet and the OMR form when you have completed the exam. When leaving, please be courteous to those still taking the exam. Good luck. Timing tip. A rate of 2.5 minutes per multiple choice problem leaves 15 minutes to write the program (worth 20 points) at the end :a, 02:a, 03:b, 04:b, 05:d, 06:d, 07:c, 08:b, 09:b, 10:a, 11:b, 12:d, 13:d, 14:a, 15:d, 16:a, 17:b, 18:d, 19:b, 20:c, 21:b, 22:c, 23:b, 24:c, 25:d, 26:c

2 1) Which of the following Python instructions does not produce an error when executed? a) lst = [ a, e, i, o, u ] lst[2:] = lst[:2] b) mst = aeiou mst[2:] = mst[:2] c) tpl = ( a, e, i, o, u ) tpl[2:] = tpl[:2] d) None of (a), (b) or (c) will produce an error. e) All of (a), (b) and (c) will produce errors. 2) What does the following expression produce as a value: [[n+1] for n in range(5) if n%2==0] a) [[1], [3], [5]] b) [1, 3, 5] c) [[0], [2], [4]] d) [0, 2, 4] e) None of the above 3) Which of the following statements regarding the use of files in Python is true? a) A file can be opened for reading or for writing, but not for both. b) Before a value can be written to a file, the file must be opened and attached to a file descriptor. c) An exception is raised if a Python program terminates before closing a file that was opened during execution of the program. d) All of (a) (c) are true. e) None of (a) (c) are true. 4) Which of the following is not a principal of object-oriented programming? a) Inheritance b) Short circuit evaluation c) Polymorphism d) Encapsulation e) Classes support all of these programming concepts. 5) Which of the following statements regarding functions is true? a) A function encapsulates an algorithm. b) An important reason to define and use functions is to modularize a program. c) In Python, a function must be defined before it can be invoked. d) All of (a) (c) are true. e) None of (a) (c) are true.

3 Figure 1 6) What output does Line 1 produce when the program in Figure 1 is executed? a) [ In, fact,, this ] b) [ tedious, was, process ] c) tedious! was process d) [ In, fact, this ] 7) What output does Line 2 produce when the program in Figure 1 is executed? a) 0 b) 5 c) 6 d) 3 8) What output does Line 3 produce when the program in Figure 1 is executed? a) [ tedious, was, process, this, fact ] b) [ tedious, was, process, this, fact, In ] c) [ was, process, this, fact, In ] d) `was process this fact, In 9) Which of the following statements regarding Python classes and instances is false? a) To initialize an instance, the init method is invoked. b) A class is invoked by the class keyword. c) Once created, an instance can be modified using assignment. d) All of (a) (c) are false. e) None of (a) (c) is false.

4 Figure 2 10) What output does Line 1 produce when the program in Figure 2 is executed? a) 1211 cents b) 23 cents c) [`12, `11, `cents ] d) an error message 11) What output does Line 2 produce when the program in Figure 2 is executed? a) 0 b) 4 c) 5 d) an error message 12) What output does Line 3 produce when the program in Figure 2 is executed? a) False, False, False b) True, True, True c) True, False, True d) True, False, False 13) What output does Line 4 produce when the program in Figure 2 is executed? a) False, False b) True, True c) True, False d) False, True 14) What output does Line 5 produce when the program in Figure 2 is executed? a) False, False b) True, True c) True, False d) False, True e) None of the above

5 15) What output does Line 1 produce when the program in Figure 3 is executed? a) say, what b) what, say c) ( say, what ) d) ( what, say ) 16) What output does Line 2 produce when the program in Figure 3 is executed? a) say what b) what say c) ( say, what ) d) ( what, say ) Figure 3 17) What output does Line 3 produce when the program in Figure 3? a) say what b) what say c) ( say, what ) d) ( what, say ) 18) What output does Line 5 produce when the program in Figure 3 is executed? a) [ a, e, i, o, u ] b) [ u, e, i, o, u ] c) [ u, e, i, o, a ] d) None 19) What output does Line 6 produce when the program in Figure 3 is executed? a) [ a, e, i, o, u ] b) [ u, e, i, o, u ] c) [ u, e, i, o, a ] d) None

6 20) What output does Line 1 produce when the program in Figure 4 is executed? a) 11 b) 9 c) 8 d) 7 21) What output does Line 2 produce when the program in Figure 4 is executed? a) 0 b) 1 c) 2 d) An error message. Figure 4: Contents of poem.txt is on the right 22) What output does Line 3 produce when the program in Figure 4 is executed? a) 0 b) 1 c) 2 d) An error message. 23) What output does Line 4 produce when the program in Figure 4 is executed? a) 0 b) 1 c) 2 d) An error message. 24) What output does Line 5 produce when the program in Figure 4 is executed? a) 14 b) Silverstein c) S. Silverstein d) An error message. 25) What output does Line 6 produce when the program in Figure 4 is executed? a) 11 b) 14 c) Silverstein d) An error message.

7 Figure 5 26) What output does Line 1 produced when the program in Figure 5 is executed? a) b) c) d) An error message. 27. Program question 20pts. Please, write on scrap paper first, then copy your answer to the next page. Make sure you put your name on the solution and hand it in at the end of the test. Background You will read in a file of information about payments made to a conference. Assume the file is named pymts.txt and it is in your current working directory. Each line of the file consists of: a 3-digit ID number a numeric amount (an integer or float) the letter c (for credit ), if the amount is a reimbursement; nothing, otherwise (i.e., if the amount is a payment). Entries in a row are separated by white space. For each person (ID), you are going to report the total paid and either the amount owed on the registration or the amount owed to the person (in case of overpayment). Assume the conference registration fee is $75. In case of overpayment, the amount should be enclosed in parentheses. For example, if pymts.txt has the following contents: c c Your program would print the table: ID Amount owed (75.00)

8 Requirements 1) Prompt for the name of the file to open. 2) Print the results out as a table with two columns: Use the headers ID and Amount owed for the two columns. Print one row for each person (ID). Separate the columns by some white space. Print two decimal places for amounts. 3) Your program must use at least one function, which you design to improve the modularity of your program. 4) To receive the full points, your program must be modular and easy to follow. Hints 1) The program should work with any file of the appropriate content, so don t report the values for the file above. Write a program! 2) Efficiency and/or elegance are not required. What matters is that it works and is modular and easy to follow! 3) You do not need to perform any error checking. 4) Be clear about your indentation!

9 CSE 231, Spring 09, Dr. Dillon, Exam 1 written solution Name: Section: def readpymts(s,d): """Read file (s) of payment info into a dictionary (d)""" fd = open(s,'r') for line in fd: entry = line.strip().split() idnum, amt = int(entry[0]), float(entry[1]) if len(entry) == 2: d[idnum] = d.get(idnum,0) + amt else: d[idnum] = d.get(idnum,0) amt fd.close() def printtable(d): """Print the table""" print "ID Amount owed" for idnum, amt in d.items(): owed = 75 - amt if owed < 0: print "%d (%.2f)"%(idnum, -owed) else: print "%d %.2f"%(idnum,owed) # get file name fname = raw_input("enter the name of the payment file: ") # create dictionary of payments pymts = {} readpymts(fname,pymts) # print table printtable(pymts)