Difference between revisions of "Advanced-C++/C2/Inheritance/English-timed"

| In this tutorial, we will learn:

|'''Inheritance''' Types of '''inheritance'''.

| To record this tutorial, I am using:

|'''Ubuntu OS '''version '''11.10'''

|'''g++ compiler '''version '''4.6.1'''

|  Let us start with an introduction to Inheritance.

|When one '''object''' acquires the property of another, it is called as '''inheritance.'''

|It is the process of reusing the existing '''class''' without modifying them.

| Types of '''Inheritance'''- '''Single level inheritance'''

|'''Multilevel inheritance''' and

|'''Hybrid Inheritance'''.

| First, let us know about the '''base class''' and the '''derived class.'''

|The '''base class''' has its own properties and functionality.

|It is also called as '''parent class.'''

|The derived class is the '''child class.'''

|'''Derived class''' inherits the properties and functionality of the '''base class.'''

|Let us see what is '''single level inheritance.'''

| In '''single level inheritance''' only one '''base class''' and '''one derived''' class is needed.

| '''Multiple inheritance'''-

|In '''multiple inheritance''', '''derived class''' inherits from more than one '''base class'''.

| '''Hierarchical Inheritance'''-

| In '''Hierarchical Inheritance''', multiple '''derived classes''' inherit from one '''base class.'''

| '''Multilevel inheritance'''-

| In '''Multilevel inheritance''', the '''subclass''' acts as the '''base class''' for other classes.

| And '''Hybrid inheritance'''-

|  In '''hybrid inheritance''', more than one form of '''inheritance''' is combined.

|  Now let us see an example on '''single level inheritance.'''

|I have already typed the code on the '''editor'''.

|Note that our file name is  '''exam_inherit.cpp'''.

| This is our '''header file''' as '''iostream'''.

|  Here, we are using the '''std namespace'''.

|  Here, we have class '''student.'''

|  Then we have an '''integer variable''' '''roll_no''' and '''character array name''', as '''private''' members of '''class student'''.

|  Function '''input()''' and function''' display()''' are the '''public''' functions of '''class student'''.

| Here we are using the '''input()''' function to accept the roll no. and name of the student.

|  Then we have the '''display()''' function to display the roll_no and name.

|  Here we have another '''class''' as '''exam_inherit.'''

|This is the '''derived class.'''

|It inherits the function and data of '''class''' '''student.'''

|  Then we have declared '''sub1, sub2, sub3''' and '''total'''

|as '''private variables''' of '''class exam_inherit.'''

|  Here we have '''input_exam()''' and '''display_exam()''' as '''public functions.'''

|Here we close the '''class''' '''exam_inherit.'''

| Now, we are using '''input_exam() '''function to accept the marks of three subjects.

|  Here, we are using '''display_exam()''' function to calculate the total of three subjects.

|Then we '''print''' a total.

|  This is our '''main()''' function.

|  Here we create an '''object''' of '''class''' '''exam_inherit''' as '''ex'''.

| Then we call all the functions using the object '''ex'''.

| And this is our '''return''' statement.

|  Let us execute the program.

| Open the '''terminal''' '''window''' by pressing '''Ctrl, Alt''' and '''T '''keys simultaneously, on your keyboard.

|  To compile, type:

|'''g++ (space) exam_inherit.cpp (space)-o (space) exam'''.

| Press '''Enter'''.Type:'''./ (dot slash) exam'''. Press '''Enter'''.

|  Here it is displayed as:'''Enter Roll no.:'''

|I will give as 1.

|'''Enter Name:'''I will enter as '''Arya'''.

|I will give as '''60''',

| '''subject 2''' as 70'''

|  05:02

| and '''subjec 3''' as 80'''.

| The '''output''' is displayed as:

|'''Roll no is: 1''''''Name is: Arya''' and

|'''Total is: 210'''.

|  Now, we will see '''multilevel inheritance''' in the same example.

|Let's switch back to our '''editor'''.

|Note that our file name is '''multilevel.cpp'''.

| Here, we have declared the variable '''total'''.

|as '''public variable''' of '''class''' '''exam_inherit.'''

|This is because the '''private''' members are not accessed by the '''derived class.'''

|  Here we have another '''class''' as '''grade.'''

|Class '''grade''' is the '''derived class'''

| and class '''exam_inherit''' is the '''base class''' for class '''grade'''.

| All the '''function'''s and '''data''' of class '''exam_inherit''' will be inherited to class '''grade'''.

| Here, we have declared '''avg''' as '''private''' member of '''class grade'''  

|and function '''average()''' as '''public''' function.

|Then we close the '''class'''.

| Here we use the '''average()''' function to calculate the average.

|Then we print the '''average.'''

| Inside the main function, we create an '''object''' of '''class grade''' as '''gd.'''

|'''gd.input()'''

|'''input_exam()'''

|'''display()''''''display_exam()'''

|and the '''average()''' function.

|  And this is our '''return''' statement.

|  Now you can see that class '''grade''' is the '''derived class.'''

| and '''exam_inherit''' is the '''base class''' for class '''grade.'''

| And here class '''exam_inherit''' is the '''derived class.'''

| And class '''student''' is the '''base class''' for class '''exam_inherit.'''

| Let us '''execute''' the program.

| Come back to our '''terminal'''.

| To compile, type:'''g++ (space) multilevel.cpp (space) -o (space) mul'''

|Press '''Enter'''.Type '''./mul'''

|Press '''Enter'''.

| Here we see, '''Enter Roll no.:'''

|I will enter as '''2'''.

|I will enter as '''Pratham'''.

|I will give as '''65''',

|subject2 as '''67''' and

|subject3 as '''82'''.

| The '''output''' is displayed as:

|'''Name is: Pratham ''''''Total is: 214 ''' and  

|'''Average is: 71'''.

|Let us move back to our '''slides'''. Let us summarize.

|In this tutorial, we learnt:

|'''Inheritance''' and * Types of '''inheritance.'''

|  As an assignment- write a program to create a '''class''' '''Shape'''.

| Then create two '''function'''s of the '''class''' as '''Area''' and '''Perimeter'''.

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