45   

    46 You can apply different Boolean operations on t now for example :

    47 

    48 

    49 f=not t , this saves the value of not t that is False in f. 

    50 

    51 We can apply other operators like or and and ,

    52 

    53 f or t gives us the value True while 

    54 f and t gives us the value false.

    55 

    56 You can use parenthesis for precedence , 

    57 

    58 Lets write some piece of code to check this out .

    59 

    60 a=False

    61 b=True

    62 c=True

    63 

    64 To check how precedence changes with parenthesis . We will try two expressions and their evaluation.

    65 

    66 do

    67 (a and b) or c 

    69 This expression gives the value True

    70 

    71 where as the expression a and (b or c) gives the value False .

    72 

    73 Now we will have a look at strings 

    74 

    75 type 

    76 w="hello"

    77 

    78 w is now a string variable with the value "hello"

    79 

    80 printing out w[0] + w[2] + w[-1] gives hlo if you notice the expression for accessing characters of a string is similar to lists . 

    81 

    82 Also functions like len work with strings just like the way they did with lists

    83 

    84 Now lets try changing a character in the string in the same way we change lists .

    85 

    86 type :

    87 w[0]='Capital H'  

    88 

    89 oops this gives us a Type Error . Why? Because string are immutable . You can change a string simply by assigning a new element to it . This and some other features specific to string processing make string a different kind of data structure than lists .  

    90