![16
Basic C++ Extension from C
• comments
/* You can still use the old comment style, */
/* but you must be // very careful about mixing them */
// It's best to use this style for 1 line or partial lines
/* And use this style when your comment
consists of multiple lines */
• cin and cout (and #include <iostream.h>)
cout << "hey";
char name[10];
cin >> name;
cout << "Hey " << name << ", nice name." << endl;
cout << endl; // print a blank line
• declaring variables almost anywhere
// declare a variable when you need it
for (int k = 1; k < 5; k++){
cout << k;
}](https://image.slidesharecdn.com/lecture1-220723024833-9863c9e5/85/Fundamentals-of-Programming-in-C-ppt-16-320.jpg)
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Fundamentals of Programming in C++.ppt
- 1. 1 CSE 459.22 Programming in C++
- 2. 2 Overview • Sign roster list • Syllabus and Course Policies • Introduction to C++ • About Lab 1 • Fill Questionnaire
- 3. 3 Introduction to C++ • Programming Concept • Basic C++ • C++ Extension from C
- 4. 4 Focus • Focus on – Programming Concepts – Programming Design Techniques • Don’t get lost in – Language Technical Details
- 5. 5 What is programming? Programming is taking A problem Find the area of a rectangle A set of data length width A set of functions area = length * width Then, Applying functions to data to solve the problem
- 6. 6 Programming Concept Evolution • Unstructured • Procedural • Object-Oriented
- 7. 7 Procedural Concept • The main program coordinates calls to procedures and hands over appropriate data as parameters.
- 8. 8 Procedural Concept (II) • Procedural Languages – C, Pascal, Basic, Fortran – Facilities to • Pass arguments to functions • Return values from functions • For the rectangle problem, we develop a function int compute_area (int l, int w){ return ( l * w ); }
- 9. 9 Object-Oriented Concept • Objects of the program interact by sending messages to each other
- 10. 10 Objects An object is an encapsulation of both functions and data • Objects are an Abstraction – represent real world entities – Classes are data types that define shared common properties or attributes – Objects are instances of a class • Objects have State – have a value at a particular time • Objects have Operations – associated set of operations called methods that describe how to carry out operations • Objects have Messages – request an object to carry out one of its operations by sending it a message – messages are the means by which we exchange data between objects
- 11. 11 OO Perspective Let's look at the Rectangle through object oriented eyes: • Define a new type Rectangle (a class) – Data • width, length – Function • area() • Create an instance of the class (an object) • Request the object for its area In C++, rather than writing a procedure, we define a class that encapsulates the knowledge necessary to answer the question - here, what is the area of the rectangle.
- 12. 12 class Rectangle { private: int width, length; public: Rectangle(int w, int l) { width = w; length = l; } main() { Rectangle rect(3, 5); cout << rect.area()<<endl; } int area() { return width*length; } }; Example Object Oriented Code
- 13. 13 Object-Oriented Programming Languages • Characteristics of OOPL: – Encapsulation – Inheritance – Polymorphism • OOPLs support : – Modular Programming – Ease of Development – Maintainability
- 14. 14 Characteristics of OOPL • Encapsulation: Combining data structure with actions – Data structure: represents the properties, the state, or characteristics of objects – Actions: permissible behaviors that are controlled through the member functions Data hiding: Process of making certain data inaccessible • Inheritance: Ability to derive new objects from old ones – permits objects of a more specific class to inherit the properties (data) and behaviors (functions) of a more general/base class – ability to define a hierarchical relationship between objects • Polymorphism: Ability for different objects to interpret functions differently
- 15. 15 Basic C++ • Inherit all ANSI C directives • Inherit all C functions • You don’t have to write OOP programming in C++
- 16. 16 Basic C++ Extension from C • comments /* You can still use the old comment style, */ /* but you must be // very careful about mixing them */ // It's best to use this style for 1 line or partial lines /* And use this style when your comment consists of multiple lines */ • cin and cout (and #include <iostream.h>) cout << "hey"; char name[10]; cin >> name; cout << "Hey " << name << ", nice name." << endl; cout << endl; // print a blank line • declaring variables almost anywhere // declare a variable when you need it for (int k = 1; k < 5; k++){ cout << k; }
- 17. 17 Basic C++ Extension from C (II) • const – In C, #define statement • Preprocessor - No type checking. • #define n 5 – In C++, the const specifier • Compiler - Type checking is applied • const int n = 5; // declare and initialize • New data type – Reference data type “&”. int ix; /* ix is "real" variable */ int & rx = ix; /* rx is “alias” for ix. Must initialize*/ ix = 1; /* also rx == 1 */ rx = 2; /* also ix == 2 */
- 18. 18 C++ - Advance Extension • C++ allows function overloading – In C++, functions can use the same names, within the same scope, if each can be distinguished by its name and signature – The signature specifies the number, type, and order of the parameters expressed as a comma separated list of argument types
- 19. 19 C++ • Is a better C • Expressive • Supports Data Abstraction • Supports OOP • Supports Generic Programming – Containers • Stack of char, int, double etc – Generic Algorithms • sort(), copy(), search() any container Stack/Vector/List
- 20. 20 Take Home Message • There are many different kinds of programming paradigms, OOP is one among them. • In OOP, programmers see the execution of the program as a collection of dialoging objects. • The main characteristics of OOPL include encapsulation, inheritance, and polymorphism.