Rossella Lau Lecture 1, DCO10105, Semester B, DCO10105 Object-Oriented Programming and Design  Lecture 1: Introduction What this course is about:  C++ programming  Object-Oriented programming concepts  Good Programming practice  Program design -- By Rossella Lau

Rossella Lau Lecture 1, DCO10105, Semester B, About C++  Created by Bjarne Stroustrup at Bell Lab about 1985  Maintains C (early 1980) with simpler usages  O-O language  Powerful, flexible  With a Standard Library and a Standard Template Library  Reference: An introduction to C++ for newbies:

Rossella Lau Lecture 1, DCO10105, Semester B, ANSI/ISO Standard C++  C++ programs are not always portable  September 1998, IS14882 has been approved as an ANS  most of today’s compilers comply with this standard GNU C++ compilers Visual C++ DevC++  The tool we will use in this course

Rossella Lau Lecture 1, DCO10105, Semester B, O-O programming concepts Usually three basic parts:  Class construction  data encapsulation  Inheritance  parent-child relationship – base class and sub-class  sub-class inherits everything from the parent class  software reuse, encapsulation  Polymorphism  A sub-class can pretend its base classes  A class allows for applying different data types through template  An expression denotes different operations through dynamic binding  Shorter/Less programming

Rossella Lau Lecture 1, DCO10105, Semester B, Good programming practice  Documentation  Comments  Naming identifiers  White space: indentation, blank lines, spaces  Coding convention  Usually there are rules, in addition to a programming language’s syntax, to be followed in order to make people in the same organization understand each other better Coding style Statement usages Reference: Guide lines for programming styles in this course

Rossella Lau Lecture 1, DCO10105, Semester B, Good practice I: Naming Convention  Naming in a programming language is always  Program id, method id, variables, constants  To name an identifier, one should observe the rules in C++; or the id cannot get past the compiler, otherwise  To follow a convention means even if an id’s name can pass the compiler, it should conform to some additional rules  In this course, the Java naming convention should be followed

Rossella Lau Lecture 1, DCO10105, Semester B, Program Design  Class design with UML (Unified Modeling Language) Diagram  Object-Oriented Design (OOD)  Encapsulation: combine data and operations in a unit  Inheritance: create new objects from existing objects  Polymorphism: same expression denotes different operations  Program design using structured programming approach  Top-down approach with step-wise refinement  Design methods with C++ features: const, &(reference)

Rossella Lau Lecture 1, DCO10105, Semester B, #include using namespace std; int main() { float area; int r; float const PI = 3.14; cerr << "Please enter radius in whole number:\n"; cin >> r; area = PI * r * r; cout << "The radius you provided was " << r << " feet and the area is about " << area << " sq feet" << endl; return EXIT_SUCCESS; } A simple C++ program: cirArea.cpp Header file specification Location of header files C++ entrance, function prototype Beginning of function body Function body, C++ statements End of function body Data Declaration I/O objects Output operators Input operators Keyword to define constant Assignment with expression string Statement terminator system-defined id

Rossella Lau Lecture 1, DCO10105, Semester B, C++ program style For non-class programs:  Header file specification  Coming with the standard library (SL) or the standard template library (STL)  Whenever a function from the SL or the STL is used, its respective header files should be specified through this “Preprocessor directives” #include  Location of header files  E.g., using namespace std;  std is ANSI/ISO standard where objects of iostream are located  A collection of functions (or methods)  main() is a necessary entrance point in a C++ program

Rossella Lau Lecture 1, DCO10105, Semester B, Preprocessor directives  Whenever a function from the SL or the STL is used, its respective header files should be specified through “Preprocessor directives” #include  It is not a C++ statement  It is processed through the “preprocessor” before the compiler has taken place

Rossella Lau Lecture 1, DCO10105, Semester B, The general process cycle of a C++ program Malik’s slide: 2:42

Rossella Lau Lecture 1, DCO10105, Semester B, Usual style of a function For each function:  Function prototype (header) typeOfFunction functionID (parameterList)  Function body: { C++ statements }  Data declaration statements  Executable statements  Syntax of basic statements are the same as in Java; Reference: Malik’s slide 2:5-30, 36-38, 43-47

Rossella Lau Lecture 1, DCO10105, Semester B, Quick revision and sample statements  Malik 2, Exercises: 7-9, 10.a-f

Rossella Lau Lecture 1, DCO10105, Semester B, Basic C++ data types  Integral  char, short, int, long, bool  unsigned char, unsigned short, unsigned int, unsigned long  Floating Point  float, double, long couble  Enumeration  user-defined data types  Note that string is not a basic data type in C++ but a class in the C++ STL

Rossella Lau Lecture 1, DCO10105, Semester B, Basic C++ Input statements  E.g., cin >> r;  cin is a predefined (in iostream) object which refers to input from keyboard  >> the input operator or extraction operator  r is the variable to store the values input from cin If r is a basic C++ data type variable, data conversion is not necessary as in Java  Multiple extraction operators on a line  E.g., cin >> length >> width;

Rossella Lau Lecture 1, DCO10105, Semester B, Basic C++ Output statement  E.g., cout << r;  cout is a predefined object which refers to output to screen  There is another predefined output object cerr which also direct output to screen; it is a good practice to direct user prompt and error messages to cerr and normal output to cout  << is the output operator or insertion opertor  Variable or literal value can be easily printed  Multiple insertion operators on a line  E.g., cout << “The length is “ << length << endl;

Rossella Lau Lecture 1, DCO10105, Semester B, Output with new line  endl is a predeined id and its value is ‘\n’  Usually,  endl is used when the last insertion operand is an identifier;  ‘\n’ is placed at the end of a literal string if the string is the last insertion operand, e.g., cout << length << “is input from the user\n”;

Rossella Lau Lecture 1, DCO10105, Semester B, Sample coding on exercises  Malik: 2 Exercise 18a,, Programming Exercises: 8,11

Rossella Lau Lecture 1, DCO10105, Semester B, Some major differences from Java  An independent executable module  Not necessary to be a class inside a program  Using template much more than inheritance and dynamic binding  An object can be referenced in three forms: a real object, a pointer, and a reference.  Does not have a “standard web site” for on-line documentation  Some on-line sites can be found through the Helpful links under the course page

Rossella Lau Lecture 1, DCO10105, Semester B, Summary  This course focus on C++ programming with advanced concepts in O-O design  C++ basic syntax is the same as Java except for program style and, of course, usage of functions in its own libraries  Before a C++ compiler is taken place, pre-process must be performed first  C++ input statement is easier than Java as it does not need numeric data conversion

Rossella Lau Lecture 1, DCO10105, Semester B, Reference  Malik: 1.9, 2, 13.3  An introduction to C++ for newbies: -- END --