To Lecture Notes

IT 212 -- Oct 26, 2020

Review Exercises

1. Define the input string
   

   s = 'cmkpeiqwpcaoeuvnmlpopl'
   

   and the regular expression
   

   r = r'[aeiou]+'
   

   After importing the Python module re, what is the output of each of these statements:
   
   1. print(re.search(r, s))
      Ans: <re.Match object; span=(4, 6), match='ei'>
   2. print(re.findall(r, s))
      Ans: ['ei', 'aoeu', 'o']
   3. print(re.split(r, s))
      Ans: ['cmkp', 'qwpc', 'vnmlp', 'pl']
   4. print(re.sub(r, "*", s))
      Ans: cmkp*qwpc*vnmlp*pl
2. What is the difference between the tuple (3, 5, 7) and the list [3, 5, 7]?
   Ans: The main difference is that tuples are immutable, which means that the can't be changed.
3. Show that the tuple (3, 5, 7) is immutable.
   Ans: Try these statements:
   

   t = (3, 5, 7)
   # Accessing tuple elements with t[1] is okay.
   print(t, t[1])
   # Changing tuple elements is not okay,  the following
   # statement will produce this error:
   # "TypeError: 'tuple' object does not support item assignment"
   t[1] = 9
   

Reading from the Web

1. Look at the this webpage:
        http://facweb.cdm.depaul.edu/sjost/it212.greeting.htm
   Write Python script to read the contents of this webpage and print it to the console.
   Ans: Script for Item 1
2. Write a script to read the contents of this page and load the contents into the dictionary d.
        http://facweb.cdm.depaul.edu/sjost/it212/rates.txt
   Ans: Script for Item 2.
3. Write a script to read the contents of this JSON page and load the contents into a dictionary using JSON serialization.
        http://facweb.cdm.depaul.edu/sjost/it212/rates.json.txt
   Ans: Script for Item 3

Lab 3

• Complete Lab 3.
• Comments about Lab 3:
  
  1. The statement
     

     import sys
     

     is needed to use
     

     sys.exit( )
     

     which exits the script immediately.
  2. Be sure to understand the difference between the SQL column names
     

     name  source_currency  target_currency  source_amount
     source_rate  target_rate  target_amount
     

     and the Python variable names
     

     name  sc  tc  sa  sr  tr  ta
     

  Check out more hints in the Lab 3 Description.