\textbf{Manipulating strings}

String indexing starts from 0, like lists.

\lstinline|s = `Hello World'|\\
\lstinline|s[0:5]| gives \texttt{Hello}\\
\lstinline|s[6:]| gives \texttt{World}\\
\lstinline|s[6::2]| gives \texttt{Wrd}\\

\lstinline|s.replace('e', 'a')| returns a new string with all e's
replaced by a.  

\lstinline|s.lower()| and \lstinline|s.upper()| return new strings
with all lower and upper case letters, respectively.