Welcome to OBJECT ORIENTED PROGRAMMING

INTRODUCTIONStructured programming was most common way to organize a program.A programming paradigm defines the methodology of designing and implementing program using the key features and building blocks of a programming language

PROCEDURAL PROGRAMMINGLays more emphasis on procedure than dataSeparates the function and data manipulated by themWhenever the definition of a type changes, the functions referring to this type must also be changed to reflect the change

PROCEDURAL PROGRAMMINGThe change in the design must also be modified to copy with the change in structure that shows procedural programming is susceptible to design changesAs design changes lead to many modification in the code this lead to increased time and cost overheads at times

OBJECT BASED PROGRAMMING In object based programming data and its associated meaningful function are enclosed in one single entity a classClass are allowed to access its interface (how the uses views) but cannot access its implementation details (how the process is actually taking place)

OBJECT BASED PROGRAMMINGWhenever any change in the definition of type users interface remains unaffected generallyThe user cannot access the data of the class directly which is possible in procedural programming the change is localized to the definition of the change function

OBJECT BASED PROGRAMMINGSubset of object oriented programmingImplement some feature of OOP like information hiding, abstraction, classes, function overloading but not implement inheritance and polymorphism

OBJECT BASED PROGRAMMINGAdvantages :overcome most shortcoming of procedural programming it localizes the changes and hide implementation details from userIt support user defined typesImplement information hiding and abstraction

OBJECT BASED PROGRAMMINGLimitation One major limitation is ability to represent real world relationships that exist among object for example both car and truck are vehicles this cannot be represented in OBP as it not support inheritance

OBJECT ORIENTED PROGRAMMINGSuperset of OBPAll the features of OBP and overcome its limitation by implementing inheritance so that real world relation among object can be represented programmatically

OBJECT ORIENTED PROGRAMMINGOOP Concepts are data abstraction, data hiding, data encapsulation, classes, objects, inheritance and polymorphism.Implementing OOP Concepts in C++Approach for writing software in which data and behavior are packed together An abstraction is a named collection of attributes and behavior relevant to modeling a given entity

OBJECT ORIENTED PROGRAMMINGA class is a named software representation for an abstractionAn object is a distinct instance of a classSoftware code in OOPs is written to define classes, objects and manipulate these object

Implementing objects Real World objects have physical characteristics (state) and behavior e.g., motorbikeCharacteristics current gear, two wheel etcBehavior braking, accelerating etc Their state is maintained through variables or data itemsTheir behaviour is implemented through function generally called methods

Mapping an Abstraction into softwareentityattributesbehaviour

Real world Abstractionsoftware{data,data}{method,method}

Implementing Data hiding, Data Abstraction and EncapsulationEncapsulation is wrapping up of characteristics and behaviour into one unitA class bind together data and its associated functions under one unit thereby enforcing encapsulationAbstraction means representation of essential features without including the background details or explanation

Implementing EncapsulationAnything that an object does not know or cannot do is excluded from the objectEncapsulation is used to hide unimportant implementation details from the objectsPacking an objects variables within the protective custody of its methods is encapsulation and this task is accomplished through classes

General structure of a class

{data,data,.}

{method,method,} Private

Protected

Public

A Class is define asClass { private: // hidden members/methods protected: //unimportant implementation details public : // exposed important details};

Implementing InheritanceInheritance is implement in C++ specifying the name of the (base) class from which the class being defined (the derived class) has to inherit from it.Class :{ derived class own features}

Abstract class and Concrete classWhich defines an interface but does not provide implementation for all its member functionAn abstract class is meant to be used as the base class from which other classes are derivedThe derived class is expected to provide implementations for the member functions that are not implemented in the base classA derived class that implements all the missing functionality is called a concrete classA concrete class drives from abstract class

Abstract class and Concrete classExample Abstract class

Shape Concrete classCircle classConcrete classRecantagle classConcrete classTriangle class

Implementing polymorphismPolymorphism is the attribute that allows one interface to be used with different situationC++ implement polymorphism through virtual functions, overloaded functions and overloaded operators.A virtual function is used to specify the interface in abstract class but its implementation details are made available in concrete class (es)Overloading means a name having two or more distinct meaning

Function Overloading A function with same name having several definitions that are differentiable by the number or types of their arguments is known as overloaded function and this process is known as function overloadingExample float sum (int a, int b); float sum (float x,float y);

Function OverloadingFunction overloading not only implement polymorphism but also reduce number of comparison in a programPush(int)Push(float)Pop(int)Pop(float)

Declaration and Definition A function argument list is known as functions signatureExample void squar (int a, float b); //function 1Void squar (int x, float y);// same signature as function 1

Declaration and DefinitionDifferent signatures void prnsqr ( int i); void prnsqr ( char c); void prnsqr ( float f); void prnsqr ( double d);

Declaration and DefinitionWhen a function name is declare more than once in a program the compiler will interpret the second (and subsequent) declaration (s) as follows :1) If the signatures of subsequent functions match the previous functions then the second is treated as a re-declaration of the first2) If the signature of the two functions match exactly but the return type differ,the second declaration is treated as an erroneous re-declaration of the first and is flagged at compile ttime as an error for example; flaot square (float f); double square (float x); // error

Declaration and DefinitionFunction with same name and same signature but different return type are not allowed in C++You can have different return types, but only if the signature are also different: float square (float f);// different signature double square (double d); // allowedIf the signature of the function differ in either the number or type of their arguments, the two function are considered to be overloaded

Questions OOPQ1 write briefly about different programming paradigms ?Q2 Discuss major OOP concepts briefly?Q3 what is the signifance of private, protected public specifiers in a class?Q4 Discuss the relation between abstract and concrete classes ?Q5 How polymorphism implemented in c++ ?Q6 How does the complier interpret more than one definitions having same name ? What steps does it follow to distinguish these ?

Questions OOPQ7 what will be the output of following program?#includeInt area (int s){Return (s*s);}Float area (int b,int h){Return (o.5 * b* h);}Int main ( ){Cout

0rganization of data and functions in OOP object objectdatafunctiondatafunctiondatafunction

Structural of procedural programmingMain functionFunctionFunctionFunctionfunctionFunctionFunctionFunctionFunction

Restrictions on Overloaded FunctionsAny two functions in a set of overloaded functions must have different argument listOverloading functions with argument lists of the same types, based on return type alone is an errorMember function cannot be overloaded soley on the basis of one being static and other non staticTypedef declarations do not define new types: they introduce synonyms for existing types,they do not affect the overloading mechanism

Restrictions on Overloaded FunctionsExample typedef char * PSTR void Print(char *szToPrint); void Print(PSTR szToPrint);The preceding two function have identical lists. PSTR is synonym for char*.

Calling overloaded functionsA function call first matches the prototypes available with number and type of arguments provided with the function call and then call the appropriate function for execution

Step involved in Finding the best matchA match: A match is found for the function callNo match: No match is found for a function callAmbiguous match: More than one defined match for the function call

Step involved in Finding the best matchSearch for exact match :if the type of the actual argument exactly matches the type of one defined instanceA match through promotion : if no exact match is found an attempt is made to achieve a match through of the actual argumentA match through application of standard C++ conversion rules : if no match or through a promotion is found an attempt is made to achieve a match through a standard conversion of the actual argument

Step involved in Finding the best matchA match through application of a user-defined conversion: if all the above mentioned step fail, then the compiler will try the user-defined conversions in combination with integral promotions and built-in conversion to find a unique match

Advantages of OOPRe-use of code : linking of code to objects and explicit specification of relations between objects allows related objects to share codeEase of comprehension: the classes can be set up to closely represent the generic application concepts and processEase of fabrication and maintenance : the concepts such as encapsulation, data abstraction allow for very clear designs when an object is going into disallowed states, which are not permitted only its methods needs to investigatedEasy redesign and extension : the same concepts facilitate easy redesign and extension

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