1 Hello friends. Welcome to this spoken tutorial on Getting started with

     2 strings.

     3 

     4 {{{ Show the slide containing the title }}}

     5 

     6 {{{ Show the slide containing the outline }}}

     7 

     8 In this tutorial, we will learn what do we actually mean by strings in

     9 python, how python supports the use of strings. We will also learn

    10 some of the operations that can be performed on strings.

    11 

    12 {{{ Shift to terminal and start ipython }}}

    13 

    14 To begin with let us start ipython, by typing::

    15 

    16   ipython

    17 

    18 on the terminal

    19 

    20 So what are strings? In Python anything within either single quotes

    21 or double quotes or triple single quotes or triple double quotes are

    22 strings. This is true whatsoever, even if there is only one character

    23 within the quotes

    24 

    25 {{{ Type in ipython the following and read them as you type }}}::

    26 

    27   'This is a string'

    28   "This is a string too'

    29   '''This is a string as well'''

    30   """This is also a string"""

    31   'p'

    32 

    33 Having more than one control character to define strings come as very

    34 handy when one of the control characters itself is part of the

    35 string. For example::

    36 

    37   "Python's string manipulation functions are very useful"

    38 

    39 In this case we use single quote for apostrophe. If we had only single

    40 quote to define strings we should have a clumsy way of escaping the

    41 single quote character to make it part of the string. Hence this is a

    42 very handy feature.

    43 

    44 The triple quoted strings let us define multi-lines strings without

    45 using any escaping. Everything within the triple quotes is a single

    46 string no matter how many lines it extends::

    47 

    48    """Having more than one control character to define

    49    strings come as very handy when one of the control

    50    characters itself is part of the string."""

    51 

    52 We can assign this string to any variable::

    53 

    54   a = 'Hello, World!'

    55 

    56 Now 'a' is a string variable. String is a collection of characters. In

    57 addition string is an immutable collection. So all the operations that

    58 are applicable to any other immutable collection in Python works on

    59 string as well. So we can add two strings::

    60 

    61   a = 'Hello'

    62   b = 'World'

    63   c = a + ', ' + b + '!'

    64 

    65 We can add string variables as well as the strings themselves all in

    66 the same statement. The addition operation performs the concatenation

    67 of two strings.

    68 

    69 Similarly we can multiply a string with an integer::

    70 

    71   a = 'Hello'

    72   a * 5

    73 

    74 gives another string in which the original string 'Hello' is repeated

    75 5 times.

    76 

    77 Since strings are collections we can access individual items in the

    78 string using the subscripts::

    79 

    80   a[0]

    81 

    82 gives us the first character in the string. The indexing starts from 0

    83 for the first character up to n-1 for the last character. We can

    84 access the strings from the end using negative indices::

    85 

    86   a[-2]

    87 

    88 gives us second element from the end of the string

    89 

    90 Let us attempt to change one of the characters in a string::

    91 

    92   a = 'hello'

    93   a[0] = 'H'

    94 

    95 As said earlier, strings are immutable. We cannot manipulate the

    96 string. Although there are some methods which let us to manipulate the

    97 strings. We will look at them in the advanced session on strings. In

    98 addition to the methods that let us manipulate the strings we have

    99 methods like split which lets us break the string on the specified

   100 separator, the join method which lets us combine the list of strings

   101 into a single string based on the specified separator.

   102 

   103 {{{ Show summary slide }}}

   104 

   105 This brings us to the end of another session. In this tutorial session

   106 we learnt

   107 

   108   * How to define strings

   109   * Different types of defining a string

   110   * String concatenation and repeatition

   111   * Accessing individual elements of the string

   112   * Immutability of strings

   113 

   114 {{{ Show the "sponsored by FOSSEE" slide }}}

   115 

   116 This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India

   117 

   118 Hope you have enjoyed and found it useful.

   119 Thankyou

   120  

   121 .. Author              : Madhu

   122    Internal Reviewer 1 :         [potential reviewer: Nishanth]

   123    Internal Reviewer 2 :         [potential reviewer: Amit]

   124    External Reviewer   :

   125