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Classes and objects till 16 aug
- 1. Basic Of C++ , Classes and Objects Presented By: Shashank Srivastava 31 July,2012 onwards
- 2. Structure of a Program 2 16 August 2012
- 3. Structure of a Program #include <iostream> - Lines beginning with a hash sign (#) are directives for the preprocessor. - In this case the directive #include<iostream> tells the preprocessor to include the iostream standard file. - This specific file (iostream) includes the declarations of the basic standard input-output library in C++. 3 16 August 2012
- 4. Structure of a Program using namespace std; - All the elements of the standard C++ library are declared within what is called a namespace, the namespace with the name std. int main() - This line corresponds to the beginning of the definition of the main function. - The main function is the point by where all C++ programs start their execution, independently of its location within the source code. 4 16 August 2012
- 5. Structure of a Program cout<<“Hello World”; cout is the name of the standard output stream in C++, and the meaning of the entire statement is to insert a sequence of characters into the standard output stream (cout, which usually corresponds to the screen). cout is declared in the iostream standard file within return 0; the std namespace The return statement causes the main function to finish. 5 16 August 2012
- 6. Basic Structure of a Program( Without Class) 6 16 August 2012
- 7. Basic input/output in C++ Standard Output By default, the standard output of a program is the screen, and the C++ stream object defined to access it is cout. cout is used in conjunction with the insertion operator, which is written as << (two "less than" signs). 7 16 August 2012
- 8. Basic input/output in C++ Standard Input The standard input device is usually the keyboard. Handling the standard input in C++ is done by applying the overloaded operator of extraction (>>) on the cin stream. The operator must be followed by the variable that will store the data that is going to be extracted from the stream. For example: 8 16 August 2012
- 9. Introduction A class is an extension of the idea of structure used in ‘C’. It is a new way of creating and implementing user defined data types. Structure : Member are public(By Default) Class: Members are private (By Default) 9 16 August 2012
- 10. Class specification When we are creating a class, we are creating a new abstract data types that can be treated like any other built in data types. Class declaration describes the type and scope of its member. Class function definitions describe how the class functions are implemented? Class Specification=Class declaration + Class function definition 10 16 August 2012
- 11. Class Declarations Data Member Member Function 11 16 August 2012
- 12. Private and public The data is hidden so it will be safe from accidental manipulation, while the functions that operate on the data are public so they can be accessed from outside the class. 12 16 August 2012
- 13. A Simple Class Data members are usually declared as private and member functions as public 13 16 August 2012
- 14. Object Creation Creates a variable s1 of type smallobj. smallobj s1 ; // Memory for x is created. Note-: In C++, the class variables are known as objects . Therefore x is called an object of type smallobj. We may also declare more than one objects in a single statements. Smallobj s1, s2, s3; 14 16 August 2012
- 15. Accessing Class members Object-name . function-name( actual arguments) 15 16 August 2012
- 16. Accessing Class members A variable declared as public can be accessed by the objects directly. 16 16 August 2012
- 17. Accessing Class members A variable declared as public can be accessed by the objects directly. 17 16 August 2012
- 18. Defining Member function Defining Member Function Outside the Inside the class class definition definition 18 16 August 2012
- 19. Member Functions Within Class Definition We can define the member function with the class to replace the function declaration by the actual function definition inside the class. Inline function 19 16 August 2012
- 20. Member Functions outside Class Definition Function that are declared inside a class have to be defined separately outside the class. 20 16 August 2012
- 21. Member Functions outside Class Definition( implementation) 21 16 August 2012
- 22. Member Functions :Some Special characteristics Several different classes can use the same function name. Membership level will resolve the issue. Membership function can access the private data of the class. A non member function can not do so. - Friend function is the exception of this A member function can call another member function directly without using dot operator. 22 16 August 2012
- 23. A C++ Program with a class 23 16 August 2012
- 24. A C++ Program with a class(Multiple Data) 24 16 August 2012
- 25. C++ objects as a data type 25 16 August 2012
- 26. Nested Function A member function can be called by using its name inside another function declaration 26 16 August 2012
- 27. Private member function Normal practices: To place all the data items in a private section and all the functions in public section But some situations may require certain functions to be hidden 27 16 August 2012
- 28. Private member function(Cont…) A private member function can only be called by another function that is a member of its class. Note: Even an object cannot invoke a private member function using dot operator 28 16 August 2012
- 29. Private member function(Cont…) If S1 is an object of class sample, then S1.read(); //illegal , object can not access the private member 29 16 August 2012
- 30. Private member function(Cont…) te Function read() can be called by the function update() to update the value of m. 30 16 August 2012
- 31. Memory allocation for objects Memory space for object is allocated when they are declared and not when the class is specified. Member functions are created and placed in the memory space only once when they are defined as apart of class specification. Since all the objects belonging to that class use the same member functions, no separate space is allocated for member functions when the objects are created. Only space for the member variable is allocated separately for each object 31 16 August 2012
- 32. Memory allocation for objects Member Function1 Memory Created when function Member Function2 is defined Object 1 Object 2 Var1 Var1 Var2 Var2 32 16 August 2012
- 33. Static Data members In general, each object contains its own separate data. If a data item in a class is declared as static , only one such item is created for the entire class, no matter how many objects there are. A static data item is useful when all objects of the same class must share a common item of information Static member variable is visible only within the class, but its lifetime is the entire program. 33 16 August 2012
- 34. Static Data members(Exp1 &Exp2) Statdata.cpp Statdata2.cp p 34 16 August 2012
- 35. Static Data members Note: The Type and scope of each static member variable must be defined outside the class definition. Because the static data members are stored separately rather than as a part of an object. Static variables are normally used to maintain values common to the entire class 35 16 August 2012
- 36. Static data member Object 1 Object 2 Var1 Var1 Var2 Var2 Static data Common to all variable the objects 36 16 August 2012
- 37. Static function A static function can have access to only other static members ( functions or variables) declared in the same class . A static member function can be called using the class name ( instead of its objects) Class-name :: function-name; However it can be called by objects of the class also. Static member can also be defined in the private region of a class also. 37 16 August 2012
- 38. Static function (Ex.) 38 16 August 2012
- 39. Objects as function arguments It is possible to have functions which accepts objects of a class as arguments, just as there are functions which accept other variables as arguments. Pass-by-value Pass-by-reference A copy of entire object is Only the address of the passed to the function objects is passed to the Any modification made to function. the object inside the Any changes made to the function is not reflected in object inside the function is the object used to call a reflected in the actual function object. 39 16 August 2012
- 40. Objects as function arguments(Ex.) 40 16 August 2012
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- 42. 42 16 August 2012