CS112 Spring 2012 Dr. Kinga Dobolyi. Exam 2. Do not open this exam until you are told. Read these instructions:

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1 CS112 Spring 2012 Dr. Kinga Dobolyi Exam 2 Do not open this exam until you are told. Read these instructions: 1. This is a closed book exam. No calculators, notes, or other aids are allowed. If you have a question during the exam, please raise your hand. 2. You must turn in your exam immediately when time is called at the end problems which add up to100 points total. 1 hour 15 minutes. Each questionʼs point value is indicated. 4. In order to be eligible for as much partial credit as possible, show all of your work for each problem, write legibly, and clearly indicate your answers. Credit cannot be given for illegible answers. 5. After the last page there is paper for scratch work. If you need extra scratch paper after you have filled these areas up, please raise your hand. Scratch paper must be turned in with your exam, with your name and ID number written on it, but scratch paper will not be graded. 6. Please write out the following statement: I pledge on my honor that I will not give or receive any unauthorized assistance on this examination. 7. Fill in the following: NAME : SIGNATURE : G# :

2 1. For the following expressions, write what value and type the last line would evaluate to in the python interpreter, or state what kind of exception would be raised (remember, there are three types of built- in exceptions we have gone over in class). If an exception is raised, you don t need to give a value just give the type of exception. (34 points) Value Type a. var = 3 var = hello var b. (1.0) c. [] d. 3 in [1,2] e. file = open( i.html, r ) #the file contains the #numbers 1 through 3, each on a separate line x = file.read() x f. file = open( i.html, r ) #the file contains the #numbers 1 through 3, each on a separate line x = file.read(2) x g. file = open( i.html, r ) #the file contains the #numbers 1 through 3, each on a separate line x = file.readlines() x

3 h. (1,2) i. 1 + str(3) j. range(3) k. len(range(3)) l. {1:1, 2:1} m. [(1,)] n. ( a,[1,2]) o. len([ a,1,[1]]) p. { a :1,1: a } q. len([[[1]]]) r. 1 +

4 2. Write a function in python called split that takes a string argument and a list of characters as a second argument. The function should return the number of occurrences of any of the characters in the string. Below are some examples: (10 points) split( hello,[ l ]) will return 2 split( hello,[ l, o ]) will return 3 split( hello,[ q ]) will return 0

5 3. Write a function called find that opens a file called input.txt for reading. Then, read in all lines in the file. If any of the lines of the file are shorter than 3 characters (excluding the newline), your code should print out FOUND IT a single time (i.e. even if all of the lines are 1 character long in a file 5 lines long, you only print FOUND IT once. Once the function has examined the entire file, it prints FINISHED. (12 points) 4. Write a function in python called maximum that takes as argument a list of integers and returns the largest element in the list. You may not use any built- in functions besides range and/or len for this question. You may assume the list will always have at least one element in it, but you may make no other assumptions. (8 points)

6 5. What does the following code output (assume we run it in the python module mode as test.py, where all the code below is inside that one file): (26 points) x = 1 def func1(list=[],y=1): print "func1 " + str(list) print "func1 " + str(x in list) print "func1 " + str(y) def func2(): y = x + 3 print "func2 " + str(y) def main(): list = [1,2] for i in list: for j in list: func2() func1() func1(y=3) func1(list) main()

7 6. True/False circle all that are true, and document your assumptions. (10 points) a. All values (not keys) in a dictionary must be unique. b. Importing a module with the syntax import module means we don t have to prepend the module s elements with the name of the module. c. The global keyword tells a function to refer to a global variable when assigning to that variable, rather than creating a local variable with the same name. d. The keys of a data dictionary can be considered a set. e. The command file = open( data.txt, w+ ) creates a new file to write to if the file doesn t exist.

8 Scratch paper