CS21: Quiz 4 Study Guide

In addition to the concepts below, you should also know the concepts from Quiz 1, Quiz 2, and Quiz 3. Many of the earlier concepts -- especially functions -- are fundamental to what we've been studying recently.

You should be able to define the following terms:

definite loop
indefinite loop
top-down design
unit testing
bottom-up development
stubbed-out function
pseudocode
file object
newline character
lists and strings as objects
list of lists

You should understand and be able to use the following Python concepts:

while (indefinite) loops
nested loops
the file methods open() and close()
definite loop on a file (e.g., for line in infile:)
the string strip(), split() methods
the list append() method
python in (and not in) operator used on lists and strings
You should also be able to write basic operations using lists and files, such as:
- read and print all lines in a file
- read all lines in a file and store as a list

Practice problems:

Write a while loop that prints out all even numbers from 2 to 20.
Write a program that reads in the following data from a file and computes the average value:
```
98
100
91
82
88
86
77
```
Given any specific definite (for) loop, write an indefinite (while) loop that performs the same computation.
Discussion question 3 on page 261
Write a function called getLetter() that asks the user for a letter and returns the given letter. Your function should check to make sure the user enters just a single letter. If the user enters anything other than a single letter, the function should ask again, until it receives valid input.

Given the assignments for s and L, what is the value and type of each expression? Try them in python to check your answers.

L = ["There are", "many", "like it,", "but this one", "is mine."]
s = "abcdefg"

len(L)

len(s)

L[3].split()

L[3].split("h")

"a" in L[2]

"DEF" in s

Trace through the following code, show the output from its entire execution, and draw the stack before the return statement in function foo:

def main():                     OUTPUT                       STACK
   print "in main"
   b = foo(5)
   print len(b)
   print b[0]
   print b[1][1]

def foo(n):
  print "in foo"
  biglist = []
  for i in range (n):
    sublist = ["h", i, i+10]
    biglist.append(sublist)
  # draw stack here
  return biglist

main()

What is the type and value of each of the following expressions:

                      value                    type
(1) biglist
(2) biglist[2]
(3) biglist[2][0]
(4) biglist[1][2]
(5) len(biglist)
(6) len(biglist[1])

Write a program that reads in a list of words from a file infile.txt into a list of strings, and then calls a function (you write) MakeAcronym that takes the list and returns a string that is the acronym of all words in the list and prints it out. For example, if the input file is:
```
Thanks
Goodness
It's
Friday
```
Your program will print out the string "TGIF"