CPSC 217 FINAL

What is the best way to create functions for a program? Give example

Top down approach, break it down into parts

ex. Program to calculate interest, break it into 3 functions

1. Get info

2. Do Calculations

3. Display results

What is the result of and how does it work?

def displayInstructions ( ):

print ("Displaying instructions")

displayInstructions ( )

print ("End")

You created a function called displayIntructions. The body of that function has the print function in it which will have the output of: "Displaying instructions"

Then you called on your newly defined function, so this executes the function (ie, its body) and then the last output is: "End"

True or false: once a function is executed one time, it can't be called again, even if you try and call the function multiple times.

False! You can reuse a function as many times as you want/is called

What is the difference between a local variable and global variable?

Local variables are stored within function bodies.

Global variables are generally defined at the beginning of the code and can be accessed anytime

Why have local variables?

Since variables are memory locations, they take up a portion of memory of the program. So by creating local variables, the memory is used up temporarily, and then once the function is executed, that memory frees up.

When a constant or a variable is in scope, we really mean...Give example

It is somewhere that it can be used. Ex. a local variable is in scope of the function it is under

What is parameter passing? What's often forgotten (2)?

Passing local variables from one function to another.

The number of parameters passed into a function, must equal the number of parameters/variables that are called on. It also needs to match exactly what is called on in the start function.

Is this correct:

def start ( ):

print (num)

No, no parameter 'num' passed into start, so it can't access that memory location called 'num'.

To fix it, must have:

def start (num):

print (num)

What does the return function do? What is often forgotten?

Give example

It communicates a copy of information out of a function (back to caller) as function ends.

THE RETURN VALUE MUST BE STORED IN THE START FUNCTION

def square (num):

result = num * num

return (result)

def start ( ):

aStr = input ("Enter a number: ")

num = int(aStr)

result = square (num)

print (result)

Difference between parameter passing and return values?

Parameter passing passes info INTO function before it executes (passes memory location of variable into function)

Return values communicate info OUT of a function as the function ends

What are some good style of functions that should be implemented?

1. Function should have a well defined task

2. Have a self-descriptive name

3. No longer than 1 screen

4. Use variable naming conventions (lower case, camel-case, or underscore)

Why should you not use global variables? Give an example

Can accidentally be changed anywhere - since they can be accessed from anywhere, makes code harder to trace

num = 1

def fun ( ):

global num #calls in global num

num = 2 #changes global num from 1 to 2

print (num)

def start ( ):

print (num) #1

fun ( )

print (num) #2, global variable changed after fun ( )

start ( )

What are some common mistakes when calling in functions (4)?

1. Not defining the function before it is called

2. Forgetting the ( ) during that start function

3. Not indenting body of function properly

4. Creating empty functions (a function must have a least 1 body instruction)

Pros and cons of defining functions

Pros:

- solution easier to visualize

- easier to test 1 feature at a time

- easier to maintain

- smaller program size

Cons:

- more complex

- tracing may seem harder as a lot of 'jumping around'

What does immutable mean?

No 'mutations'/changes allowed

Name the 3 types of simple variables

Integer, boolean, float

Name the 3 types of composite/aggregate variables

Lists, tuples, strings

In a programming language, a list is implemented as an ...

array

How would you access a whole list vs just one element in that list? What is another name of accessing one element of the list?

aList = [1,2,3]

print (aList) # whole

print (aList[i]) #1 element

INDEXING

Create a list with a fixed size and the same data for each element.

aList = [" ! "] *3

3 elements of ! in list

output: ['!', '!', '!']

For lists, your index should be _____ and ranging from ____

1. positive integer

2. 0 to (list size -1)

What are the 2 steps needed to create a list?

1. Create variable that refers to a list

ex aList = [ ]

2. Initialize list with elements

ex. aList.append (3)

Declaring a list will result in ___ memory locations...Name them

2

one location for list itself (ie., a building)

another location contains address of list (ie., address of building)

True or false:

You can't pass a list as a parameter

False!

You can, you are passing a reference to a list and it can be modified/appended

True or false:

You must return a list variable in the start function.

Give an example and what is another name for this

False.

Since the address of the list is created in the start function is actually modified, you do not need to return it.

ex.

def start ( ) :

classGrades = initialize()

#classGrades is list reference address, it was passed from initialize function's return value

Pass by reference

True or false:

You should NOT assign a new value to the reference of a list when passing reference.

True.

If you make changes to a list/reference to a list, are those change permanent? Explain and give an example

No, if you make changes to the parameters in a function, they are only made locally. To pass these modified lists, you must return the variable name with which the reference to the list is assigned to.

Ex.

def createList ():

aList = [3,2,1]

return (aList) #passing aList to other functions after this function ends

def Function (aList):

aList[0] = 888

return (aList) #returning modified list to start function

def start ():

aList = createList ()

print (aList)

aList = Function (aList)

print (aList)

start ()

output:

[3, 2, 1]

[888, 2, 1]

How can you avoid overflowing a list? Give an example

Use a constant! It controls how many times you traverse/step through the list

ex. SIZE = 10

...

for i in range (0,SIZE,1)

What is a Python specific way to avoid overflow? Example?

Use len () which is the length function built into python

ex.

for i in range (0, len(aList) ,1)

True or false:

2D list is a list containing rows of 1D lists.

True

Given:

table = [ [0,0,0],

[1,1,1],

[2,2,2],

[3,3,3] ]

How would you get it to display this list as an actual table?

How about 1 row at a time?

Table:

for r in range (0,4,1)

for c in range (0,3,1)

print (table [r] [c], end="")

# r/c stop 1 over the actual number or r/c because the it stops ONE BEFORE!!!!

1 row at a time:

for r in range (0,4,1)

print (table [r])

Given:

table = [ [0, 0, 0],

[1, 1, 1],

[2, 2, 2],

[3, 3, 3] ]

What will be the output of the following?

1. print(table)

2. print(table[0])

3. print(table[3][1])

4. print(table[0][0][0])

1. entire list

[ [0, 0, 0],

[1, 1, 1], [2, 2, 2], [3, 3, 3] ]

2. first row

[0,0,0]

3. 4th row, 2nd column

3

4. error

What's happening here:

MAX_COLUMNS = 5

MAX_ROWS = 3

ELEMENT = "*"

aList = []

r=0

while (r < MAX_ROWS):

tempList = [ELEMENT] * MAX_COLUMNS

aList.append(tempList)

r=r+1

print (aList)

2D list is created by creating a 1D list and appending this 1D list to the end of the 2D list

1

12

123

[['', '', '', '', '*']]

[['', '', '', '', ''], ['', '', '', '', '']]

[['', '', '', '', ''], ['', '', '', '', ''], ['', '', '', '', '*']]

What are shallow copies? Give an example.

A copy of what is stored in the variable name reference (location of a list)

list1 = [1,2,3]

list2 = list1

they are both referencing the location of the list

What are deep copies? Give an example

Copies info from one list to another

list1 = [1,2,3]

list2 = [0]*3

list2[0] = list1[0]

print (list1)

print (list2)

output:

[1,2,3]

[1,0,0]

How can you boundary check a 2D list? (6)

1. for r in range (0,SIZE,1):

2. if, elif, else statements..

if (50 <= randomNum <= 80)

3. create a true/false condition

outOfBounds = True

while (outOfBounds == True):

4. add in empty row

world.append(tempRow)

5. create a function

def isOut (row,col):

outside = False

if....

6. create while loops

What are the 3 steps to dynamically create a list?

1. create variable that refers to empty list

grid = [ ]

2. successively create rows

for r in range (0,SIZE,1):

grid.append ([ ]) #need this so can add elements to end in step 3

3. EACH ROW IS A 1D LIST, add elements to the end of each row from 1D list

for c in range (o,SIZE,1):

grid [r].append("*")

# the [r] specifies which row the loop will add elements to on the end

Given:

table = [ [0, 0, 0],

[1, 1, 1],

[2, 2, 2],

[3, 3, 3] ]

What is the output of the following:

1. table.append ([2,7,1])

print (table)

2. table[3].append (3)

print (table)

3. table[2][1].append(888)

print (table)

1. adds [2,7,1] to end of table list

2. adds and extra element '3' in row 3

[3,3,3,3]

3. error! can't append to an integer...can only add onto end of list in this case

Strings are just a series of ____

Characters

True or false:

Composites types can be treated as only one entity.

Give an example

False!

Composites can also be treated as individual parts

print(aString) prints whole string

print(aString[1]) prints the 2nd character of that string

What are:

- mutable types

- constants

- immutable types

Mutable: memory location CAN change

Constants: shouldn't change

Immutable: original memory location WON'T change

True or false:

Lists are immutable. Give an example

False. Lists can be changed

ex.

aList = [1,2,3]

aList[0] = 10

print(aList) # [10,2,3]

True or false:

Strings are immutable. Give an example.

True. Strings CANNOT be edited.

ex.

s1 = "bye"

print (s1) # bye

s1[0] = "G" #ERROR, can't modify characters in a string

What are the two substring operations?

1. Slicing will return a portion of the string based on the indices given

2. Splitting divides a string into portions

Given

aString = "abcdefghij"

What will be the output of:

1. temp = aString[2:5]

2. temp = aString[:5]

3. temp = aString[7:]

1. Start at 2 go to up to but not including 5

cde

2. Start at 0 and go up to but not including 5

abcde

2. Start at character 7 and go to end

hij

Given:

aString = "James,Tam"

What will be the output of:

first,last = aString.split(",")

James Tam

What are some examples of string testing functions? What do they do?

They see if a given BE has been met (True or False)

isalpha ( )

isdigit ( )

isalnum ( )

islower ( )

isupper ( )

isspace ( )

What are some examples of functions that return modified copies of strings?

lower ( ) #returns copy of string with only lower case

upper ( ) #returns copy of string with only upper case

lstrip ( ) #leading whit spaces removed

rstrip ( ) #trailing white spaces removed

strip ( ) #removed all leading/trailing whitespaces removed

lstrip(char) #leading instances of character in parameter removed

rstrip(char) #trailing instances of character in parameter removed

What will the outputs be of the following:

1. aString = "talk1! abouT"

aString = aString.upper()

2. aString = "xxhexllo"

aString = aString.lstrip("x")

3. aString = "thxerex"

aString = aString.rstrip("x")

1. TALK1! ABOUT

2. hexllo

3. thxere

What are tuples?

Like lists, but immutable.

Tuple is a composite type, and elements can be any other type

What will the output be?

tup = (1,2,"foo",0.3)

print (tup)

print (tup[2])

tup[2]="bar"

1. (1,2,'foo',0.3)

2. foo

3. error because can't change immutable

True or false:

Functions in python can only return 0 or 1 items.

True

if had:

return (1,2,3), it's just returning ONE tuple with 3 elements

How can you 'unpack' a tuple with multiple elements? Given an example

def fun ( ):

return (2,10) #2 elements in tuple

num1,num2 = fun ( ) #2 memory locations for 2 elements of tuple

What are the 5 modes when opening a file in python? Give an example

r - open for reading

w - open for writing

c - open file for reading or writing, if no file then create one

n - create new file for reading or writing, if file exits the overwrite it

a - open file for appending, create one if it doesn't exist

ex. file = input("Enter file name:")

inputfile = open(file, "r")

True or false:

Reading a file is done within the body of a loop, each execution of the loop will read a character from the file into a BE.

False.

Yes, reading is done within the body of a loop, but each iteration of the loop will read a LINE from the file into a string

True or false:

The loop continues to read liens from the file even if there are no more line with characters.

False, it terminates as soon as end of information from file is reached

When writing a file you need __ and __. And the second one will only take a __

An input file

Output file

String parameter

ex. outputFile.write(temp)

What are the 4 error handling exceptions for files?

while (inputFileOk == True):

*Try:

body of file reading/opening

*Except IOError:

react to error

Else:

do this is no error occurs

Finally:

always do this

To create a dynamic list when reading information in from a file, use ___

Append

Who, what and when are the first microprocessor?

Intel

4004

1970

What is a microcomputer? What is it sometimes called?

A computer that uses a microprocessor.

PC (Personal Computer)

What was the fist computer for home users called?

Altair

What two companies did IBM approach as possible vendors of an OS to run it's computers?

Digital Research and Microsoft

What was the difference between Digital Research's CP/M operating system and PC/MS-DOS (Microsoft disk operataing system)

CP/M would reboot if the wrong floppy disk was in and all your work would be lost

PC/MS-DOS would ask if you wanted to save, reboot or retry if the wrong disk was in, so you could swap disks and retry

When did IMB release their first PC? What were some softwares that developers wrote for it?

1981, ran on Microsoft OS

Word processing

Accounting software

Games

Spreadsheets

True or false:

Apple entered the microcomputer market later than IBM, and thus IBM took over sales

False

Apple got into the market first, but because there were so many software developed for IBM's PC, it dominated

True or false:

IBM-PC was made with in-house parts.

False. Parts were off the shelf, so people could customize/build their own PC

What was compaq?

A new PC company opened by 3 ex-Texas Instruments employees. Ran on MS-DOS....after this more opened.

What happened when Dell and other companies joined the market?

IBM lost control

True or false:

Microsoft won the clone wars

Why?

They had MAC GUI (graphical user interface)

When did the Apple I Computer come out?

1976

What was special about the Apple II Computer released in 1977 (2)?

Had colour graphics that were superior to more posh computers. And had VisiCalc

Who invented the first graphical interface?

Xerox Star pioneered the Graphical Use Interface in 1981

A tour of the Xerox PARC inspired Apple to make?

Apple Lisa 1983, which had GUI

What was Laika and who sent her to space?

A dog and USSR

What did the USA do in response to Russia launching Sputnik (2)?

Changed school requirements

What did ARPA (Advanced Research Projects Agency) do?

To get different computers to communicate, but communication between different interfaces was lacking

What was ARPANET?

The first computers were connected via ARPANET, started with two host computers at UCLA and Stanford

What other two host computers were added to ARPANET in 1969?

University of California and University of Utah

What were the 4 milestones of the internet?

1972

Email intoduced by Ray Tomlinson

1989

Ideas of WWW appear in a paper

1990

ARPANET shut down, Archie (internet search program) developed at McGill and first web browser written

1991

WWW release to public

***First was internet and the WWW

What are the WWW milestones (3)?

1989

Tim Berners-Lee and others wanted to make it easier to share research, documents linked via http (hyper text transfer protocol), documents available for reading and downloading

1990

WWW renamed Nexus

1993

Mark Andreeseen of NCSA lauched Mosaic X (Firefox)

True or false

Before the WWW, the internet was largely used by a niche group

True

After WWW, internet usage soared

Who invented the mouse when and why?

Douglas Engelbart 1962

To create a better way for humans and computers to communicate

Name some areas of computer science

Human-Computer Interaction (HCI)

Graphics

AI

Vision

Software Engineering

Security

Games

True or false:

Software should be written to make it as easy as possible for the user to complete their task

True

What is user-centered design? Benefits?

Getting users involved and getting feedback from the beginning of the program writing process.

Cost reduction, because can make changes as you go

Computer graphics are mainly concerned with ___

manipulating and producing images...making things look 'real'

What are the 4 areas of computer graphics?

Animations (motion)

Modeling (structures)

Rendering (textures/details)

Image Processing (modifying images)

What are some areas of AI?

Expert systems (getting knowledge stored in database) and neural networks (building structures that work like neurons, ie., pattern recognition)

What is the Turing Test?

a test for intelligence in a computer, requiring that a human being should be unable to distinguish the machine from another human being by using the replies to questions put to both.

Interpreting and understanding visual information, such as FaceID, is what?

Computer vision

The main concerns of software engineers are:

Producing on time and on budget

What are the difference between the waterfall development process and Agile Software Development?

Waterfall (one-way):

1. gather requirements

2. design system

3. implement and test system

4. verify with user

5. maintain system

Traditional approach, works well for larger orjects

Agile:

- broken into parts

- all 5 of the above stages are worked on for weeks

- show shareholders

- easier to go back and change things

- smaller projects

A design pattern is __

a way of creating software that has proven to work well under a number of different contexts

(past programs that worked!)

True or false:

Many security breaches are due to machine failure.

False

Humans because of social engineering

Cryptography is __

transmitting and sorting sensitive information

What areas of computer science apply to game programming?

All

HCI

Graphics

AI

Vision

Software engineering

Security