Abstract Class

An abstract class is a class that is only meant to be inherited from. Objects cannot be created from generic classes.

To make a class abstract one of the virtual methods is made abstract by assigning it a value of zero. To make a concrete class the virtual method must be implemented in the inheriting class.

class A
{
virtual void AbstractMethod() = 0;
// The '= 0' makes the method a pure virtual
// function.
// The pure virtual function makes the class
// abstract.
};

class B: public A
{
void AbstractMethod();
};

void B::AbstactMethod()
{
}

GCC Under DOS

Getting GCC to compile under DOS is not simple.








Are there some pre-compiled binaries that I can use?

DJGPP (DJ's GNU Programming Platform)
A complete 32-bi C/C++ development system for Intel 80386 and higher PCs running DOS. This looks very old. It has not been updated since 1998.

MinGW: Minimalist GNU for Windows
A collection of freely available and freely distributable Windows specific header files and import libraries.
Looks like a very current system.
Installed MSYS. It looks like it has the same path problems that cygwin does.

General C++ Compilers

Click the picture to go to the site.


This is a real nice little package. Fits on top of the Migw port of GCC (GNU Compiler Collection): http://www.bloodshed.net/devcpp.html


This has a whole bunch of 'free' compilers.






Perhaps the greatest single piece of software contributing to software free world.

Command Line Compilers

Being really old school I like to run compiles from the command line. Especially when I am trying to learn about the language and not the IDE (Integrated Development Environment).

On a side note I find acronyms a night mare. I can forget ones I have used for years and also forget the one I just learned at the most inopportune moments. It makes me look really dumb.

I really like to run them for emacs. It just give me a sense of control at a low level.

Web Sources

The web is huge on this subject. These are just some of the links I am using.



I love this site. There is no registration and tutorials and other articles are great.

http://www.cplusplus.com/

Book Sources

These are the main books I am using for C++.

Teach Yourself C++, Second Edition by Herbert Schildt.

I really like his book. It is clear and easy to understand. However, it is also a little light on some topics and/or the index is a little week.

It look like it might be a good idea to get the third edition: http://www.geek.com/hwswrev/tyc++3.htm




Teach Yourself C, Third Edition, by Herbert Schildt.

Together with his book on C++ it is also clear and easy to understand.









C++ Primer, by Stanly B. Lippmon. Nice book, but seems a bit aged. I don't use it much.

So often I simply look it up on the web I am wondering it books will be come a thing of the past.

namespace

namespace - declares a block in which other identifiers may be declared. An identifier declared within a namespace becomes a "sub-identifier" linked to the surrounding namespace identifier. It creates a names scope.

This is a good web page on namespace: http://www.cplusplus.com/doc/tutorial/namespaces.html

namespace myNamespace
{
int a, b;
}


myNamespace::a
myNamespace::b

#include
using namespace std;

namespace first
{
int var = 5;
}

namespace second
{
double var = 3.1416;
}

int main()
{
cout << first::var << endl;
cout << second::var << endl;
return 0;
}

Using the 'using' keyword the namespace can be accessed.

namespace first
{
int x = 5;
}

using first::x;

using namespace first;

cout << x << endl;

both of the above using lines would make the x variable available.