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
• 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()
• the string strip(), split() methods
• the list append() method
• python in (and not in) operator used on lists and strings
• list of lists
• strings and lists as objects
• 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:

1. Write a while loop that prints out all even numbers from 2 to 20.
2. Write a program that reads in the following data from a file and computes the average value:

   98
   100
   91
   82
   88
   86
   77
   

3. Given any specific definite (for) loop, write an indefinite (while) loop that performs the same computation.
4. Discussion question 3 on page 261
5. 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.
6. Given the following:

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

   what is the value and type of each expression? Try them in python to check your answers.

   (1) len(L)
   (2) len(s)
   (3) L[3].split()
   (4) "a" in L[2]
   (5) "DEF" in s
   

7. 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])
   

8. 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"