Member Functions And Member Data Computer Science Essay Free Essay Example

There are many linguistic communications for composing plans. We shall hold an overview of C++ programming linguistic communication and utilize it to compose plans. Modern plans are normally designed utilizing a method known as object-oriented scheduling ( OOP ) . Object Oriented Method of programming is based on the hierarchy of categories, and good defined objects. OOP is organized around the objects. In this method a plan is viewed as a aggregation of interacting objects. The chief features of OOP are encapsulation, heritage and polymorphism.

C++ accommodates OOP by supplying categories, an expanded construct of a information construction, which alternatively of keeping informations merely, can keep both informations and maps.

A category is a information type whose variables are objects. Where as an object is a variable that has member maps every bit good as the ability to keep informations values. [ Problem Solving with C++ by Walter Savitch, Sixth Edition ] . The major belongingss of the category are Data Encapsulation and Inheritance. Encapsulation is a signifier of information concealment or abstraction.

Uniting a figure of variables and maps, into a individual bundle, as an object of a category is called encapsulation. Objects have algorithms that describe how it should act in different state of affairss.

A category can incorporate members that are of a category type or arrows, mentions to a category type. Data members include members that are declared with the cardinal types, including arrows, mention, array types, spot Fieldss and user defined types.

MEMBER FUNCTIONS AND MEMBER DATA

There are many sorts of maps that can be declared merely as category members.

These are called particular member maps. These maps affect the manner objects of a category are created, destroyed, copied and converted into objects of other types. when a member map is declared as changeless by utilizing a keyword const, so this map is merely a read merely map. These maps can be called implicitly.

In this context we shall hold a expression about the undermentioned particular member maps:

Builders

Destructors

Copy builder

Assignment operator

Friend map

ACCESS SPECIFIERS

Access specifier determines the entree to the member map or member informations that follows it, up to the following entree specifier or the terminal of the category declaration. The category allows us to utilize all right control over entree rights to category constituents. The entree rights to each category constituent is indicated by utilizing the cardinal words public, private and protected. The keywords divide the category range into sections. There can be any figure of public, protected and private sections in any order you want. Public entree specifier affects all members until the following entree specifier. Whereas private entree specifier affects all members until the category terminal.

The default entree to category members is private ; the default entree to struct and brotherhood members is public. Class members which are declared as private can be used merely by member maps and friends of the category. Class members declared as protected can be used by member maps, friends of the category and categories derived from the category. Class members declared as public can be used by any map. Protected entree is an intermediate degree of informations protection between private and public.

It is really common for some portion of an object to necessitate low-level formatting before it can be used. C++ allows objects to initialise themselves when they are created. This automatic low-level formatting is performed through the usage of a builder map. When specifying a category a particular sort of member map can be defined known as builder.

Builder

“ A builder map is a particular map that is a member of a category and has the same name as that category. ” [ C++ The Complete Reference by Herbert Schildt, Second Edition ]

A builder is a map that is automatically called when an object of the category is declared. A builder is defined in the same manner as member map, except the two stairss:

Both the category name and the builder name should be same.

Neither a builder declaration nor the builder definition includes a return value.

Builders can non be called explicitly as regular member maps. Builders will be executed when the new object of category is created. The definition of the builder is same as member maps. Suppose we wanted to add a builder for initialising the side for an object, we include a builder which is shown below.

category square

{

int *side ; & lt ; — — — — — – arrow variable

populace:

square ( int ) ; & lt ; — — — — — – builder

~square ( ) ;

int country ( )

{

return ( *side * *side ) ;

}

} ;

In this category we notice that the name of builder is the same as the category. Finally the builder is topographic points in the public subdivision of the category definition. Here we observe that the variable is declared as a arrow.

“ A arrow is the memory reference of a variable ” . There are two particular arrow operators: ‘ * ‘ and ‘ & A ; ‘ . The ‘ & amp ; ‘ is a unary operator that returns the memory reference of its operand. The ‘* ‘ is a unary operator that returns the value located at the reference that follows.

Example utilizing a builder:

# include & lt ; iostream & gt ;

utilizing namespace venereal disease ;

category square & lt ; — — — — category

{

int *side ;

populace:

square ( int ) ; & lt ; — — — — builder

~square ( ) ; & lt ; — — — — destructor

int country ( )

{

return ( *side * *side ) ;

}

} ;

square: :square ( int s ) & lt ; — — — — builder definition

{

side= new int ;

*side=s ;

}

int chief ( )

{

square sqr ( 4 ) ; & lt ; — — — — object

cout & lt ; & lt ; ” AREA OF THE SQUARE IS: “ & lt ; & lt ; sqr.area ( ) & lt ; & lt ; endl ;

system ( “ intermission ” ) ;

}

End product

AREA OF THE SQUARE IS: 16

This plan calculates the country of the square utilizing builder and destructor. Here we observe that a category named square is defined where in it has the declaration of variables and a method country. A builder by category name is defined and declared along with a destructor. An object is been created utilizing the category and the country of square is calculated by utilizing the method from the category.

A builder that do non hold any statements is called DEFAULT CONSTRUCTOR. If we define a category and include perfectly no builders of any sort, so a default builder will be automatically created. This default builder does non make anything, but it does give an uninitialized object of the category type, which can be assigned to a variable of the category type. If the category definition includes one or more builders of any sort, no builder is generated automatically.

The new component shown on the line of the builder definition is called the low-level formatting subdivision. The low-level formatting subdivision goes after the parenthesis that ends the parametric quantity list and before the gap brace of the map organic structure. The low-level formatting subdivision consists of a colon followed by a list of some or all the member variables separated by commas. Each member variable is followed by its initialising value in parentheses.

Aside from executing the particular function of low-level formatting, builder maps are no different from other types of maps. This includes overloading.

Dynamically allocated variables do non travel off unless the plan makes a delete. If the dynamic variables are non eliminated, so the dynamic variables will go on to busy memory infinite. Which may do the plan to abort by utilizing up all the memory in the free shop director. This can be handled by utilizing a member map called a destructor.

DESTRUCTOR

“ A destructor is a member map that is called automatically when an object of the category passes out of range. “ [ Absolute C++ by Walter Savitch, Third Edition ]

The destructor has the same name as builder, but it is preceded by a ‘~ ‘ . Like a builder, a destructor has no return type, non even the type nothingness. A destructor has no parametric quantities. Therefore, a category have merely one destructor which can non be overloaded.

Collection

Classs that have objects of other categories as their informations members are called composite categories. In object orientated design, utilizing objects of one category as constituents for objects of another category is called CLASS AGGREGATION or CLASS COMPOSITION.

The term collection is used to depict the construction of a category or an object whose encapsulated informations includes cases of other user defined categories. The encapsulated objects are refered with the word subobject.

ASSIGNMENT OPERATOR AND OTHER OVERLOADING OPERATOR

The values from one object are copied to another bing object by utilizing the assignment operator. The assignment operator is of low precedency. It has to be performed after all other looks are completed.

A builder which is called whenever a new variable is created from an object is called a COPY CONSTRUCTOR. A transcript builder is by and large called when an object is created from another object of same type, passed by value as a parametric quantity to a map and returned from a map.

If it is non defined in a category, the compiler itself defines a transcript builder. [ codersource.net ]

Both transcript builder and assignment operator are largely likewise, i.e. , both copy one object to another. However, the assignment operator transcripts to bing objects, and the transcript builder transcripts to freshly created objects.

If a new object has to be created before the copying occurs, so the transcript builder is used. If a new object does non hold to be created before the copying occurs, so the assignment operator is used.

The transcript builder is called alternatively of the assignment operator in the undermentioned state of affairss:

1. When instantiating one object and initialising it with values from another object.

2. When go throughing an object by value.

3. When an object is returned from a map by value.

FRIEND FUNCTIONS

A friend map is a map that is non member of the category but has entree the category ‘s private and protected members. Friend maps are normal external maps which are given particular entree privileges but, they are non considered as category members. These maps are non in category ‘s range, and non called utilizing member choice operators unless they are members of other category.

# include & lt ; iostream & gt ;

utilizing namespace venereal disease ;

category com

{

private:

int aa, BB, m, N ;

populace:

nothingness areaa ( int m ) & lt ; — — — — Function Overloading

{ cout & lt ; & lt ; ” area of the square is: “ & lt ; & lt ; m*m & lt ; & lt ; endl ; }

nothingness areaa ( int m, int N )

{ if ( m & gt ; n ) cout & lt ; & lt ; m & lt ; & lt ; ” is greater “ & lt ; & lt ; m & lt ; & lt ; ” and “ & lt ; & lt ; n & lt ; & lt ; endl ;

else cout & lt ; & lt ; n & lt ; & lt ; ” is greater among “ & lt ; & lt ; m & lt ; & lt ; ” and “ & lt ; & lt ; n & lt ; & lt ; endl ; }

nothingness setd ( int R, int I ) & lt ; — — — — Inline map ( implicit )

{

cout & lt ; & lt ; ” Enter existent portion “ & lt ; & lt ; endl ;

cin & gt ; & gt ; R ;

aa= R ;

cout & lt ; & lt ; ” Enter fanciful portion “ & lt ; & lt ; endl ;

cin & gt ; & gt ; I ;

bb=i ;

}

friend com attention deficit disorder ( com fd1, com fd2 ) ; & lt ; — — — – Friend Function

inline nothingness show ( )

{

cout & lt ; & lt ; ” The complex figure after adding the two existent and fanciful parts is: “ & lt ; & lt ; aa & lt ; & lt ; “ + i “ & lt ; & lt ; bb & lt ; & lt ; endl ;

}

} ;

com attention deficit disorder ( com fd1, com fd2 )

{

com fd3 ;

fd3.aa=fd1.aa+fd2.aa ;

fd3.bb=fd1.bb+fd2.bb ;

return ( fd3 ) ;

}

nothingness chief ( )

{

int l=0 ;

int m=0 ;

com K1, K2, K3 ;

K1.setd ( cubic decimeter, m ) ;

K2.setd ( cubic decimeter, m ) ;

K3=add ( K1, K2 ) ;

K3.display ( ) ;

K1.areaa ( 4 ) ;

K1.areaa ( 2,8 ) ;

system ( “ intermission ” ) ;

}

The above plan shows the use of a friend map. Using the friend map we can entree the categories private and public informations. The private variables are used to read the values of the user. Using the friend map the variables are added and it displays the end product utilizing the show map from the category. In this plan we find the overloading map. Over lading a map is non but giving same name to two maps with more or less parametric quantities passed. The maps which are defined in the category are called inline maps. They are of two types “ inexplicit inline “ and “ expressed inline ” The end product as shown below.

Decision

By the terminal of this assignment it is clear, how to utilize the builders, destructor, entree specifier, member informations and maps, friend map, assignment operator, transcript builder, overloading of maps in categories in C++ .

Mention

C++ The Complete Reference by Herbert Schildt, Second Edition

Problem Solving with C++ by Walter Savitch, Sixth Edition

Absolute C++ by Walter Savitch, Third Edition

World Wide Web. codersource.net

hypertext transfer protocol: //msdn.microsoft.com/en-us/library/5tk49fh2 ( VS.80 ) .aspx