Page 306 - Computer Science Class 11 With Functions
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12.1.4 Length of a String

        To find the length of a string, Python provides a the built-in function len() which returns the length of a string. For
        example,
         >>> len('hello')
              5
         >>> len('hello\nhow are you')
              17
         >>> len('hello\n\n\nhow are you')
              19
        As the character sequence \n denotes a single end-of-line character, it is counted only once while computing the
        length of the string.

        12.1.5 Concatenation of Strings
        The + operator is used to concatenate two strings. For example,

         >>> 'Hello,' + 'How are you?' + 'I am good.' + 'How are you'
              'Hello,How are you?I am good.How are you'
         >>> 'Hello, ' + 'How are you? ' + 'I a good. ' + 'How are you'
              'Hello, How are you? I am good. How are you'
        12.1.6 Multiplication Operator

        The multiplication operator (*) produces a string, concatenated with itself a specified number of times. For instance,
        the expression 'Hello'*5  yields the string 'HelloHelloHelloHelloHello', i.e. the string 'Hello'
        repeated five times (second operand:5). As expected, the expression 'Hello'*0 yields an empty string as the string
        'Hello' is repeated zero times.

         >>> 'Hello'*5
              'HelloHelloHelloHelloHello'
         >>> 'Hello'*0
              ''
        The multiplication operator is quite useful when we want to print a pattern. For example, to print a 4-line pattern with
        a single * in the first line, two *'s in the second line, three *'s in the third line, and finally, four *'s in the fourth line,
        we simply invoke the print() function as follows:

         >>> print('*' + '\n' + '*'*2 + '\n' + '*' * 3 + '\n' + '*' * 4)
              *
              **
              ***
              ****

               len(): Returns the length of a string.
               Operator +: Used to concatenate two strings.
               Operator *: Concatenates a string with itself, a specified number of times.



        12.1.7 Reverse of a String

        Now we are ready to write a function reverse(str1) that generates a string having characters in the reversed sequence
        of the original string; for example,
         >>> reverse('excellent')
              'tnellecxe'
         >>> reverse('tnellecxe')
              'excellent'




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