Lecture 9: Exam I Review

Transcription

1 CS 111 (Law): Program Desig I Lecture 9: Exam I Review Robert H. Sloa & Richard Warer Uiversity of Illiois, Chicago September 22, 2016

2 This Class Discuss midterm topics Go over practice examples Aswer ay questios

3 Learig programmig 1) Expect it to be differet! 2) Do t feel you eed to memorize it 3) Immersio == Experimetatio

4 The Secret of Happiess is (i programmig) Do t memorize! Look at examples of similar problems Experimet Sytax that looks weird ow will become secod ature soo

5 Midterm I: Topics Covered Variables Mathematical operators Statemets Types Strigs, slicig, []s, fid() Fuctios while, if-else; simple for

6 Midterm I: Topics, cotiued What is a algorithm, computer, RAM, etc. Ecryptio Ecryptio keys ad govermet access Computer Fraud ad Abuse Act ad visitig websites

7 Ay geeral questios?

8 What type of variable would you use to store the legth of a plaitext? A. it B. float C. list D. boolea E. strig

9 What type of variable would you use to store the legth of a plaitext? A. it B. float C. list D. boolea E. strig

10 What type would you use for a variable to store the fractio of Chicago wards with more tha 20 homicides per 100,000 populatio? A. it B. float C. list D. boolea E. strig

11 What type would you use for a variable to store the fractio of Chicago wards with more tha 20 homicides per 100,000 populatio? A. it B. float C. list D. boolea E. strig

12 What type would you use for a variable to store whether a plaitext cotais ay space characters? A. it B. float C. list D. boolea E. strig

13 What type would you use for a variable to store whether a plaitext cotais ay space characters? A. it B. float C. list D. boolea E. strig

14 What type would you use for a variable for that plaitext? A. it B. float C. list D. boolea E. strig

15 What type would you use for a variable for that plaitext? A. it B. float C. list D. boolea E. strig

16 What type would you use for the set of all of the URLS of web pages liked to by a page? A. it B. float C. list D. boolea E. strig

17 key ="LEMON" Write a expressio that returs the last character i key Write a expressio that returs every other positio i this key, startig with the first

18 key ="LEMON" Write a expressio that returs the last character i key. key[-1] or key[le(key) - 1] Write a expressio that returs every other positio i this key, startig with the first key[::2]

19 Computer Fraud ad Abuse Act You are coviced your bak has poor olie security. To prove it, you access your accout ad copy iformatio from it that oly bak employees ca ordiarily see. You violate the Computer Fraud ad Abuse Act if you accessed the bak website (a) itetioally. (b) without authorizatio (c) Itetioally ad without authorizatio.

20 Computer Fraud ad Abuse Act You are coviced your bak has poor olie security. To prove it, you access your accout ad copy iformatio from it that oly bak employees ca ordiarily see. You violate the Computer Fraud ad Abuse Act if you accessed the bak website (a) itetioally. (b) without authorizatio (c) Itetioally ad without authorizatio.

21 The 4 th ad 5 th Amedmet (a) The 4 th ad 5 th Amedmet protect agaist govermet searches. (b) The 4 th Amedmet protects agaist selficrimiatio. (c) The 5 th Amedmet protects agaist govermet searches. (d) The 4 th Amedmet protects agaist govermet searches ad the 5 th Amedmet protects agaist self-icrimiatio.

22 The 4 th ad 5 th Amedmet (a) The 4 th ad 5 th Amedmet protect agaist govermet searches. (b) The 4 th Amedmet protects agaist selficrimiatio. (c) The 5 th Amedmet protects agaist govermet searches. (d) The 4 th Amedmet protects agaist govermet searches ad the 5 th Amedmet protects agaist self-icrimiatio.

23 Suppose you have the followig fuctio defied: def square(x): retur x**2 Write a fuctio that takes itegers x ad y ad prits x squares of umbers i a row, startig with y^2. Do't forget the docstrig!

24 Solutio def myfu(x,y) : """takes itegers x ad y ad prits x squares of umbers i a row, startig with y^2""" couter = 0 while couter < x: prit(square(y + couter)) couter = couter + 1 # or couter += 1

25 def foo(x) : x = x + x[1] def bar(y) : prit("foo:" + x) y = y*2 prit("bar:", y) foo(y) retur y What does bar("silly ) retur? bar( silly ) y = silly y = y*2 y = sillysilly prit( bar:, y) does t chage y foo( sillysilly ) x = sillysilly x = x+x[1] x = sillysillyi prit( foo:, x) does t chage x or y retur y sillysilly What is the output of bar("silly )? Make sure to write ot oly the retur statemet but everythig that happes whe the fuctio is called. bar:sillysilly foo:sillysillyi sillysilly

26 def foo(x) : x = x + x[1] prit("foo:" + x) What does bar("silly ) retur? error whe you load the def of bar because ame x is ukow! def bar(y) : y = y*2 prit("bar:", y) foo(y) retur x Sytax error at load time we ever get to call bar before we fix it

27 def foo(x): x = x + x[1] prit("foo:" + x) What is the output of maifu( )? You may fid it helpful to draw a picture of what's happeig i memory as you trace through the program. def bar(y): y = y*2 prit("bar:", y) foo(y) retur y def maifu( ): z = 3 w = bar("madess"*z) prit(z) prit(w) bar:madessmadessmadessmadessmade ssmadess foo:madessmadessmadessmadessmade ssmadessa 3 MadessMadessMadessMadessMadessM adess

28 Try this 1. Write a pytho fuctio called gauss that takes as iput a positive iteger N ad returs the sum N 2. Write a pytho fuctio called sumofsquares that takes as iput a positive iteger N ad returs the sum N 2 You ca write extra helper fuctios too!