Page 438 - Computer science 868 Class 12
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17.  A Happy number is a number in which the eventual sum of square of digits of the number is equal to 1. For example,
                     68  Sum of square of digits = 6  + 8  = 100
                                               2
                                           2
                                               2
                                            2
                     100 Sum of square of digits = 1  + 0  + 0  = 1
                                                   2
                     Then 68 is a happy number. Design a class Happy to check if a given number is a happy number or not. Some of the members of
                    the class are given below.
                     Class name                       :  Happy
                     Data Members
                     n                                :  stores the number
                     Member Methods
                     Happy ()                         :  constructor to assign 0 to n
                     void getnum(int nn)              :  to assign the parameter value to the number, n = nn
                     int sumSq digits(int)            :  return the sum of square of the digits of number
                     void isHappy ()                  :  checks  if  the  given  number  is  a  Happy  number  by  calling  the  function
                                                         SumSqdigits(int) and displays appropriate message
                     Specify the class Happy by giving details of the constructor, void getnum(int), int sumSqdigits(int) and void isHappy(). Write the
                    main function to create object and call other functions.
                 18.  Design a class Prime to check if a given number is a prime number or not. [A number is said to be prime if it is only divisible by 1
                    and itself].
                     Example: 3, 5, 7, 11, 13, 17, 19, 23, 29, etc. Some of the members of the class are given below:
                     Class name                       :   Prime
                     Data Members/Instance variables:
                     num                              :  to store the number
                     Methods/Member functions
                     Prime (int nn)                   :  parameterised constructor to initialise the data member num=nn
                     int countfactors(int i)          :  returns the count of the factors of the number(num), using a recursive technique
                     void check()                     :  checks whether  the given number is  prime  or not by  invoking  the  function
                                                         countfactors(int) and displays the result with an appropriate message
                     Specify the class Prime giving details of the constructor(), int countfactors(int) and void check(). Define a main() function to create
                    an object and call the functions accordingly to enable the task.
                 19.  Design a class Pattern which will accept number of lines as n and print the pattern. If n = 5 the pattern is
                     12345
                     2345
                     345
                     45
                     5
                     The details of the class are given below.
                     Data Members
                     int n                            :  to store number of lines
                     Member Methods
                     void read(int nn)                :  initialise nn to n
                     void print(int i, int j)         :   using  the concept of  recursion  design  the method  print(int, int)  which  will
                                                         generate the above pattern
                     static void main()               :  create object and call the other methods
                 20.  Design a class Palindrome to check if a given number is a palindrome number or not. [A number is said to be palindrome if it reads
                    same from both ends]. Example: 121, 55, 3223, 45754, etc. Some of the members of the class are given below:
                     Class name                       :   Palindrome
                     Data Members/Instance variables
                     num                              :  to store the number
                     rev                              :  to store reverse





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