Topics Covered on Wednesday, 2010-08-04

Objects and Classes

• Abstract Objects
  • Have attributes (e.g. colour, make, etc.)
  • Have operations (e.g. start, drive, brake, etc.)
• Abstract Objects can be instantiated
  • Instantiated Abstract Object is an Object
• In Object-Oriented Programming, an Abstract Object is a Class
  • An instance of a Class is an Object

Sample program

1  // hello.cpp
2  // Print "Hello, world" on the display
3  // Copyright (C) 2010, Raj Mathur
4  #include <iostream>
5  using namespace std;
6  int main(int argc, char *argv[])
7  {
8    cout << "Hello, world" << endl;
9    exit(0);
10 }

• Lines 1-3 are comments, ignored by the compiler.
• Line 4 is a preprocessor directive and is replaced by the contents of the file "iostream".
• Line 5 is required, ignore for now.
• Line 6 is a function definition. Every function definition consists of the function return type (the range), the name of the function, the arguments to the function and the function body.
• Every C++ program must have one and only one function named main. Execution begins on the first executable statement of main.
• Lines 7-10 are the function body.