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#+TITLE:     
#+AUTHOR:    FOSSEE
#+EMAIL:     
#+DATE:    

#+DESCRIPTION: 
#+KEYWORDS: 
#+LANGUAGE:  en
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* 
#+begin_latex
\begin{center}
\vspace{12pt}
\textcolor{blue}{\huge Manipulating Strings}
\end{center}
\vspace{18pt}
\begin{center}
\vspace{10pt}
\includegraphics[scale=0.95]{../images/fossee-logo.png}\\
\vspace{5pt}
\scriptsize Developed by FOSSEE Team, IIT-Bombay. \\ 
\scriptsize Funded by National Mission on Education through ICT\\
\scriptsize  MHRD,Govt. of India\\
\includegraphics[scale=0.30]{../images/iitb-logo.png}\\
\end{center}
#+end_latex
* Objectives
  At the end of this tutorial, you will be able to,

 - Slice strings and get sub-strings out of them.
 - Reverse strings.
 - Replace characters in strings. 
 - Convert strings to upper or lower case.
 - Join a list of strings.
* Pre-requisite
  Spoken tutorial on -
  - Getting started with strings.
  - Getting started with lists.
  - Basic datatypes and operators.
* Forms
 - sat
 - saturday
 - Sat
 - Saturday
 - SAT
 - SATURDAY
* Exercise 1
 - Obtain the sub-string excluding the first and last characters from
  the string ~s~.
* Exercise 2
  - Given a list week, week = ~week = ["sun", "mon", "tue", "wed",
  "thu", "fri", "sat"]~. Check if ~s~ is a valid name of a day of the
  week. Change the solution to this problem, to include forms like,
  SAT, SATURDAY, Saturday and Sat.
* Exercise 3
 - Given ~email~ -- ~info@fossee[dot]in~

  Replace the ~[dot]~ with ~.~ in ~email~
* Exercise 4
 - From the ~email\_str~ that we generated, change the separator to be a
  semicolon instead of a comma.
* Summary
  In this tutorial, we have learnt to, 

 - Obtain sub-strings and reverse of strings by using the index numbers
 - Use following functions -
    - ``upper()'' -- to obtain the upper case of a string
    - ``lower()'' -- to obtain the lower case of a string
    - ``replace()'' -- to replace a character by another one
    - ``join()'' -- to join a list of strings with an operator

* Evaluation
1. Given a string s = "this is a string", how will you change it
   to "this isn't a list" 

2. Given the string "F.R.I.E.N.D.S" in s, obtain the string "friends".

* Solutions
1. 
#+begin_src Python
s = s.replace("string", "list")
s = s.replace("is", "isn't")
s
#+end_src

2. s[::2].lower()

* 
#+begin_latex
  \begin{block}{}
  \begin{center}
  \textcolor{blue}{\Large THANK YOU!} 
  \end{center}
  \end{block}
\begin{block}{}
  \begin{center}
    For more Information, visit our website\\
    \url{http://fossee.in/}
  \end{center}  
  \end{block}
#+end_latex