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authorPuneeth Chaganti2010-10-13 11:13:01 +0530
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Getting started with strings LO - script and questions.
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+.. Objectives
+.. ----------
+
+.. At the end of this tutorial, you should know --
+
+.. 1. How to define strings
+.. #. Different ways of defining a string
+.. #. How to concatenate strings
+.. #. How to print a string repeatedly
+.. #. Accessing individual elements of the string
+.. #. Immutability of strings
+
+.. Prerequisites
+.. -------------
+
+.. 1. getting started with ipython
+
+.. Author : Madhu
+ Internal Reviewer :
+ External Reviewer :
+ Checklist OK? : <put date stamp here, if OK> [2010-10-05]
+
+Script
+------
+
+{{{ Show the slide containing the title }}}
+
+Hello friends. Welcome to this spoken tutorial on Getting started with
+strings.
+
+{{{ Show the slide containing the outline }}}
+
+In this tutorial, we will learn what do we actually mean by strings in
+python, how python supports the use of strings. We will also learn
+some of the operations that can be performed on strings.
+
+{{{ Shift to terminal and start ipython }}}
+
+To begin with let us start ipython, by typing::
+
+ ipython
+
+on the terminal
+
+So what are strings? In Python anything within either single quotes
+or double quotes or triple single quotes or triple double quotes are
+strings. This is true whatsoever, even if there is only one character
+within the quotes
+
+{{{ Type in ipython the following and read them as you type }}}::
+
+ 'This is a string'
+ "This is a string too'
+ '''This is a string as well'''
+ """This is also a string"""
+ 'p'
+
+Having more than one control character to define strings come as very
+handy when one of the control characters itself is part of the
+string. For example::
+
+ "Python's string manipulation functions are very useful"
+
+In this case we use single quote for apostrophe. If we had only single
+quote to define strings we should have a clumsy way of escaping the
+single quote character to make it part of the string. Hence this is a
+very handy feature.
+
+The triple quoted strings let us define multi-lines strings without
+using any escaping. Everything within the triple quotes is a single
+string no matter how many lines it extends::
+
+ """Having more than one control character to define
+ strings come as very handy when one of the control
+ characters itself is part of the string."""
+
+We can assign this string to any variable::
+
+ a = 'Hello, World!'
+
+Now 'a' is a string variable. String is a collection of characters. In
+addition string is an immutable collection. So all the operations that
+are applicable to any other immutable collection in Python works on
+string as well. So we can add two strings::
+
+ a = 'Hello'
+ b = 'World'
+ c = a + ', ' + b + '!'
+
+We can add string variables as well as the strings themselves all in
+the same statement. The addition operation performs the concatenation
+of two strings.
+
+Similarly we can multiply a string with an integer::
+
+ a = 'Hello'
+ a * 5
+
+gives another string in which the original string 'Hello' is repeated
+5 times.
+
+Since strings are collections we can access individual items in the
+string using the subscripts::
+
+ a[0]
+
+gives us the first character in the string. The indexing starts from 0
+for the first character up to n-1 for the last character. We can
+access the strings from the end using negative indices::
+
+ a[-2]
+
+gives us second element from the end of the string
+
+Let us attempt to change one of the characters in a string::
+
+ a = 'hello'
+ a[0] = 'H'
+
+As said earlier, strings are immutable. We cannot manipulate the
+string. Although there are some methods which let us to manipulate the
+strings. We will look at them in the advanced session on strings. In
+addition to the methods that let us manipulate the strings we have
+methods like split which lets us break the string on the specified
+separator, the join method which lets us combine the list of strings
+into a single string based on the specified separator.
+
+{{{ Show summary slide }}}
+
+This brings us to the end of another session. In this tutorial session
+we learnt
+
+ * How to define strings
+ * Different ways of defining a string
+ * String concatenation and repeatition
+ * Accessing individual elements of the string
+ * Immutability of strings
+
+{{{ Show the "sponsored by FOSSEE" slide }}}
+
+This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India
+
+Hope you have enjoyed and found it useful.
+Thank you!
+