Last Week

  Function Pointers
  Object Oriented C

Overview

  Intro to C++

  History   
  Extensions of C
  class 
       access
       methods



Intro to C++
============

History 

 C with class invented by Bjarne Stroustup around 1981
 ATT  in order to build telephone switch simulations.  
 Based the language on lessons learned from Simula '67
 a language designed to write simulation programs.

 C with classes was little more than what we saw last week.
 i.e. struct with member functions.


Extensions to C

1.	Most C programs can be compiled with 
	C++ (some type problems)
2.	Classes !
3.	overloaded (what is that?) methods + functions
	   void push(int);
           void push(float); 
4.      New input/output

 
 class 

Basic unit to declare an object


class point {
  public:
    point (int x, int y);
    move (int dx, int dy);
  private:
    int x;
    int y;
};

>> How is this different from Java?

   private and public sections
   No code in class (just declarations) 

>> You would probably put this in a header file point.h


#ifndef POINT_H
#define POINT_H

  class point {...}

#endif


>> What does the #ifndef do for you?
>> In the .cc you put the method definitions


<class name>::<method name>
point::point (int x1, int y1) 
{
   x = x1; y = y1;
}

>> What do x and y refer to?


>> Write and compile a program hello.cc


#include <iostream.h>

main () {

  cout <<  "hello world" << endl;

}


>> compiling 

  $ g++ -o hello hello.cc

Input-Output

 cout --stdout
 cin   '' stdin
 cerr  --stderr

 usage is different 
 int x;
 float y;

  cout << "this is an int " << x << " and this is a float " << y <<endl;

  
  cin >> x;
  cin >> y;