# HG changeset patch
# User Puneeth Chaganti <punchagan@fossee.in>
# Date 1286534480 -19800
# Node ID 8018779e02b75d32be9dc2983bcfcc59867b8daa
# Parent  5734d03b026ce16b90a574c7143e0253df889747
Added questions to manipulating strings LO.

diff -r 5734d03b026c -r 8018779e02b7 manipulating-strings/questions.rst
--- a/manipulating-strings/questions.rst	Fri Oct 08 13:12:25 2010 +0530
+++ b/manipulating-strings/questions.rst	Fri Oct 08 16:11:20 2010 +0530
@@ -1,17 +1,94 @@
-Objective
----------
+Objective Questions
+-------------------
+
+.. A mininum of 8 questions here (along with answers)
+
+1. Given the list week::
+
+     ["sun", "mon", "tue", "wed", "thu", "fri", "sat"]
+
+   ``"Sun" in week`` returns True or False?
+
+   Answer: False
+   
+#. Given the string ``s = "palindrome"``, what is returned by s[4:]
+
+   Answer: ``ndrome``
+
+#. Given the string ``s = "palindrome"``, what is returned by s[-4]
+
+   Answer: ``r``
+
+#. Given the string ``s = "palindrome"``, what is returned by s[4::-1]
 
-.. A mininum of 8 questions here. 
+   Answer: ``nilap``
+
+#. Given the string ``s = "palindrome"``, what is returned by s[-4:]
+
+   Answer: ``rome``
+
+#. Given a string ``s = "this is a string"``, how will you change it
+   to ``"this isn't a list"`` ?
 
-1. Question 1
-2. Question 2
-3. Question 3
+   Answer::
+   
+     s = s.replace("string", "list")
+     s = s.replace("is", "isn't")
+
+#. Given a string ``s = "this is a string"``, how will you change it
+   to ``"THIS ISN'T A LIST"`` ?
+
+   Answer::
+   
+     s = s.replace("string", "list")
+     s = s.replace("is", "isn't")
+     s = s.upper()
 
+#. Given a line from a CSV file (comma separated values), convert it
+   to a space separated line. 
 
-Programming
------------
+   Answer: line.replace(',' ' ')
+
+#. Given the string "F.R.I.E.N.D.S" in s, obtain the friends. 
+
+   Answer: ``s[::2].lower()
+
+Larger Questions
+----------------
+
+.. A minimum of 2 questions here (along with answers)
+
+1. Given the string friends, obtain the string "F.R.I.E.N.D.S". 
+
+   Answer::
+   
+     s = "friends"
+     s = s.upper()
+     s_list = list(s)
+     ".".join(s_list)
 
-.. A minimum of 2 questions here. 
+2. Given a string with double quotes and single quotes. Interchange
+   all the double quotes to single quotes and vice-versa. [Solve it
+   for this particular string. Not a generic one. Solve it for a
+   generic string, if you know how to iterate over a list.]
+
+   s = """ "Isn't this a 'simple' task?" "No, it isn't." "Yes! it is." """
+
+   Answer::
+   
+     s = s.replace('"', '#')
+     s = s.replace("'", '"')
+     s = s.replace('#', "'")        
 
-1. Programming Assignment 1
-2. Programming Assignment 2
+   .. depends on ``for`` which is not an LO dependency a generic string. 
+   
+   For generic string
+   Answer:: 
+
+     S = []
+     s_list = s.split("'")
+
+     for s_s in s_list:
+         S.append(s_s.replace('"', "'"))
+
+     s = '"'.join(S)
diff -r 5734d03b026c -r 8018779e02b7 manipulating-strings/script.rst
--- a/manipulating-strings/script.rst	Fri Oct 08 13:12:25 2010 +0530
+++ b/manipulating-strings/script.rst	Fri Oct 08 16:11:20 2010 +0530
@@ -7,13 +7,14 @@
 .. #. Reverse strings
 .. #. Replace characters in strings. 
 .. #. Convert to strings to upper or lower case
+.. #. joining a list of strings
 
 .. Prerequisites
 .. -------------
 
 ..   1. getting started with strings
 ..   #. getting started with lists
-..   #.
+..   #. basic datatypes
      
 .. Author              : Puneeth 
    Internal Reviewer   : 
@@ -31,9 +32,9 @@
 
 In this tutorial we shall learn to manipulate strings, specifically
 slicing and reversing them, or replacing characters, converting from
-upper to lower case and vice-versa 
+upper to lower case and vice-versa and joining a list of strings.
 
-#[punch: reversed returns an iterator. should we still teach it?]
+.. #[punch: reversed returns an iterator. should we still teach it?]
 
 We have an ``ipython`` shell open, in which we are going to work,
 through out this session. 
@@ -199,13 +200,43 @@
    email = email.replace("[dot]", ".")        
    print email
 
+Now, let's look at another interesting problem where we have a list of
+e-mail addresses and we wish to obtain one long string of e-mail
+addresses separated by commas or semi-colons. 
+
+::
+
+  email_list = ["info@fossee.in", "enquiries@fossee.in",  "help@fossee.in"]
+
+
+Now, if we wish to obtain one long string, separating each of the
+email id by a comma, we use the join operator on ``,``. 
+
+::
+
+  email_str = ", ".join(email_list)
+  print email_str
+
+Notice that the email ids are joined by a comma followed by a space. 
+
+Following is an exercise that you must do. 
+
+%%3%% From the email_str that we generated, change the separator to be
+a semicolon instead of a comma. 
+
+Please, pause the video here. Do the exercise and then continue. 
+
+::
+
+  email_str = email_str.replace(",", ";")
 
 That brings us to the end of the tutorial. 
 
 {{{ show summary slide }}}
 
 In this tutorial, we have learnt how to get substrings, reverse
-strings and a few useful methods, namely upper, lower and replace. 
+strings and a few useful methods, namely upper, lower, replace and
+join. 
 
 {{{ Show the "sponsored by FOSSEE" slide }}}