Index

1. Python While Loop

• #!/usr/bin/python
  
  
  n = 12
  i = 1
  while i<=12:
      print i,"x 8 =", i*8
      i=i+1
  print "hello world"

2. Python Functions

• #!/usr/bin/python
  
  def mult8(i):
      return i*8
  
  
  for i in range(1,13):
      print i,"x 8 =", mult8(i)

3. if statement and functions

• #!/usr/bin/python
  
  def mult8(i):
      print i,"x 8 =", i*8
      if i<12:
          mult8(i+1)
  
  mult8(1)

4. Python Modules

• there are many Python modules available
• which cover many topics
  • networking modules
  • graphic modules, OpenGL, GUI, graphing
  • mail, http, telnet, pop3, imap modules
  • operating system modules
• html parsing modules
• examine the Python modules python online docs

5. urllib

• used to download files from servers using
  • ftp, http and local file access

6. urllib example

• #!/usr/bin/python
  
  from urllib import urlretrieve
  
  
  urlretrieve(’http://floppsie.comp.glam.ac.uk/index.html’,
              ’temp.html’)

7. urllib example

• #!/usr/bin/python
  
  
  import os
  import urllib
  Version = ’1.5’
  filename = ’python-%s.tar.gz’ % Version
  remoteaddr = ’ftp://ftp.python.org/pub/python/src/’
  print "attempting to download a file", filename,
  print "from", remoteaddr
  urllib.urlretrieve(remoteaddr + filename,
                     filename)

• in this example the contents of the string being passed to the function (method) is incorrect
  • the python file has moved, so see if you can locate a similar file on the remote website and then modify the above code to download this new file
  • hint use a browser to navigate to the correct file, then cut and paste the url into your code
    

8. smtp module

• Simple Mail Transport Protocol is the most common protocol whereby email is transmitted across the Internet

• #!/usr/bin/python
  
  import smtplib, string, sys, time
  
  mailserver = "localhost"
  
  From = string.strip(raw_input(’From: ’))
  To = string.strip(raw_input(’To: ’))
  Subject = string.strip(raw_input(’Subject: ’))
  
  Date = time.ctime(time.time())
  Header = (’From: %s\nTo: %s\nDate: %s\nSubject: %s\n\n’
            % (From, To, Date, Subject))
  
  
  Text = "my message"
  server = smtplib.SMTP(mailserver)
  failed = server.sendmail(From, To, Header + Text)
  server.quit()
  if failed:
      print ’failed to send mail’
  else:
      print ’all done..’

9. Testing your mail program

• $ python sendmail1.py

10. Python Gotya’s

• be careful to ensure that your code is indented correctly
• be very careful not to name your file to a name used by a library you are importing
• for example do not call this file string.py

• #!/usr/bin/python
  
  import string
  
  
  words=string.split(’hello world again’)
  print words

• the python interpreter will read your file twice
  • one when you run the file
  • and again when it comes across the import string !
• name the file teststring and it will work fine
  • if you did call it string.py and run then you will need to remove string.py and also string.pyc
    

11. Tutorial

• type in the urllib example given during the lecture and check that it works
  • now modify this example so that your script prompts the user for
    • the url
    • the local file name
• write a python program which writes some text to a file (hint see file handling in python notes)
• write a python program which appends some text to the file
• write a python program which reads the contents of a file and displays it on the screen
• now write a python program which prints a small menu and depending upon the input choice (1, 2, 3) calls, a function:
  • to write text to a file
  • to append text to a file
  • to read the file and display the contents

Index

This document was produced using groff-1.19.