Facts about computers and IT Field.

1.A byte means 8 bits and a nibblemeans 4 bits.

2.First harddisk available was of 5MB

3.Ethernet is the registered trademark 0f Xerox.

4.google uses over 10000 network computers to crawl the web.

5.Google can be queried in 26 languages

6.The floopy disk was patented byallen shugart in 1946.

7.More than 80% of web pages are in english.

8. 88% percent web pages have very low traffic rate.

9. An average american is dependent on 250 computers.

10.Internet is most fastest growing platform for advertisement.

11.About one third of CDs are pirated

12.About 76% softwares used in india are pirated.

13.Only 10% of the webpages are used by the search engines

14."I am feeling Lucky" This button is used by negligible no of people on net.

15.Bill gates & Paul Allen started a company called Traf-O-Data to

monitor traffic flow.

16.The four largest software makers in the world are:

(a) Microsoft

(b) Adobe

(c) Sap

(d) Computer Associates.

17.Top Ten Supercomputers of Today's Generation Arranged according to the speed:

1. Bluegene/ L DD2 Beta-system (IBM).

2. Columbia (NASA).

3. Earth Simulator (NEC).

4. MareNostrum(Bar celona Supercomputer Center).

5. Thunder (Lawrence Livermore National Laboratory).

6. ASCI Q(Los Alamos National Laboratory).

7. System X(Virgina Tech).

8. Blugene/L DD1 Prototype(IBM).

9. eServer pSeries 655 cluster (Naval Oceanographic Office).

10. Tungsten(National Center ForSupercomputing Applications).

By: Adnan Khalil On 06:27

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C++ Tutorial

1. Introduction

1.1. Why do people program?

1.2. What is C++ & OOP?

1.3. What do I need to program?

2. Your first program

2.1. Running a C++ program

2.2. C++ program structure

2.3. Comments

2.4. Libraries

2.5. Functions

2.6. Streams

2.7. Return

3. Number Systems

3.1. Decimals

3.2. Binaries

3.3. Hexadecimals

4. Exercises

4.1. EX 1 : Running

4.2. EX 2 : Typing

4.3. EX 3 : Converting

5. What now?

5.1. Good programming sites

5.2. Good books on C++

1.INTRODUCTION

1.1. Why do People Program?

Each person can have his own reason for programming but I can tell you that programming is one of the best ways to gain a deep understanding of computers and computer technology. Learning to program makes you understand why computers and computer programs work the way they do. It also puts some sense into you about how hard it is to create software.

1.2. What is C++ & OOP?

C++ is an extended version C. C was developed at Bell Labs, in 1978. The purpose was to create a simple language (simpler than assembly & machine code...) which can be used on a variety of platforms. Later in the early 1980's C was extended to C++ to create an object-oriented language. O(bject) O(riented) P(rogramming) is a style of programming in which programs are made using Classes. A class id code in a file separate from the main program - more on classes later. OOP in general & C++ in particular made it possible to handle the complexity of graphical environments. (like windows, macintosh..)

1.3. What do I need to program?

Well, you need a computer and a compiler to start with but you also need some curiosity and a lot of time. I guess(!?) you have a computer. You can find different compilers for free from borlands website (Check 5.1). If you have the curiosity but lack in time read stuff at lessons and detention hours. Read whenever you find time. Having a good C++ book (check 5.2) also helps a lot. (and is much better for your eyes) One thing not to forget: No tutorial, book, program or course makes you a programmer in 5 days. YOU make yourself a programmer. NO compiler writes an entire program for you, YOU write the program.

2. YOUR FIRST PROGRAM

2.1. Running a C++ Program

Read this part carefully: A C++ program must be compiled and linked before it can be executed, or run, on the computer. A great lot of compilers do this automatically. So what is a compiler? A compiler is a program that translates C++ code into machine language. Machine language is the language consisting of 1s and 0s, and is the native language of a computer. A typed C++ program is called the source-code, and the compiled code is called the object code.

Before the object code can be executed, it must be linked to other pieces of code (e.g. included libraries) used by the program. The compiled & linked program is called an executable file. Finally, the program is executed by the system. It's output is displayed in a window.

2.2. C++ Program Structure

All C++ progs contain statements (commands) that tell the computer what to do. Here is an example of a simple C++ program:

/* Downloaded from code.box.sk

We own you program */

# include <iostream.h>

int main()

{

cout<<"We own you"; // the first statement

return(0); // the second statement

}

Run the program. It should display :

We own you

The structure of a simple C++ program is:

/* Comments : Name, purpose of the program 

your name, date, etc. */

# include <librarynames.h>

int main()

{

statements; // comments

return(0);

}

Now we will have a closer look on the structure:

2.3. Comments

Comments are used to explain the contents of a program for a human reader. The computer ignores them. The symbols /* and */ are used for the beginning and end of a comment for multi-line comments. // symbols are also used for commenting. All characters on a line after the // symbol are considered to be comments and are ignored. Most newbies think that commenting a program is a waste of time. They are wrong. Commenting is very important because it makes the code understandable by other programmers and makes it easier to improve a program or fix the bugs in it. You'll understand better after trying to decipher a hundred pages of code you wrote a few months later.

2.4. Libraries

Look at the program above. Following the opening comment was the line:

# include <iostream.h>

This line simply tells the computer that the iostream library is needed therefore it should be included. A library is a collection of program code that can be included (and used) in a program to perform a variety of tasks. iostream is a library - also called as a header file, look at its extension - used to perform input/output (I/O) stream tasks. There are a lot of non-commercial C++ libraries for various purposes written by good guys who spent more than enough time in front of their computers. You can find them at code.box.sk. Also references to all libraries used in the tutorials can be found on the net.

2.5. Functions

The next line in the program was:

int main()

Which is the header of the main function. Makes sense? No? A function is a set of statements that accomplish a task. A function header includes the return type of the function and the function name. As shown in the main() header, main returns an integer(int) through return(0). So all the functions that have an integer as the return type returns integers. Very clear. The statements in a function (in this case the main function) are enclosed in curly braces. The { and } symbols indicates the beginning and the end of statements. More on functions later.

2.6. Streams

What is a stream? In C++ input/output devices are called streams. cout (we used above) is the c(onsole) out(put) stream, and the send (insertion) operator is used to send the data "We own you" into the stream. In the first statement:

cout<<"We own you";

The words following the << operator are put in quotation marks(") to form a string. When run, the string We own you is sent to the console output device. Yes, it is also called the computer screen.

Important note: C++ is case sensitive. That means cout and Cout is not the same thing.

2.7. Return

The second statement was:

return(0);

which causes the program to terminate sending the value 0 to the computer. The value "0" indicates that the program terminated without error.

Note: The statements end with a semicolon (;). A semicolon in C++ indicate the end of a statement.

3. DATA & NUMBER SYSTEMS

3.1. Decimals

The base 10 number system. Uses 10 digits: 0 to 9. Numbers raised to the zero power is equal to one. For example: 5 to the power 0 = 1. Base ten equivalent of the number 

2600 = 2 x (10 to the power 3) + 6 x (10 to the power 2)

33 = 3 x (10 to the power 1) + 3 x (10 to the power 0)

3.2. Binaries

The base 2 number system. Uses 2 digits : 0 and 1. Works the same as base 10 except we multiply numbers by the powers of 2 instead. For example 110 is equal to 6 in base 10:

110 = 1 x (2 to the power 2) + 1 x (2 to the power 1) = 6(base10)

3.3. Hexadecimal

The base 16 number system. Uses 16 digits. 0 to 9 & "A" to "F". Works the same as base 10 & base two except the numbers are multiplied by the powers of 16 instead:

1B = 1 x (16 to the power 1) + 2(B) x (16 to the power of 0) = 30(base10)

4. EXERCISES

4.1. Running

Find & install a compiler, type the example program and run it. Pretty simple but be sure the syntax is correct.

4.2. Typing

Make a program which displays your name without looking to this tutorial. Makes you learn a lot better.

4.3. Converting

Convert these to decimals : 110101, 001101, 10101110

Convert these to hexadecimals : 234, 324, 19394

Convert these to binaries : 2F, 1B3, 234, 125

By: Adnan Khalil On 06:25

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List of Malwares::

1. Viruses. The malware that’s on the news so much, even your grandmother knows what it is. You probably already have heard plenty about why this kind of software is bad for you, so there’s no need to belabor the point.

2. Worms. Slight variation on viruses. The difference between viruses and worms is that viruses hide inside the files of real computer programs (for instance, the macros in Word or the VBScript in many other Microsoft applications), while worms do not infect a file or program, but rather stand on their own.

3. Wabbits. Be honest: had you ever even heard of wabbits before (outside of Warner Bros. cartoons)? According to Wikipedia, wabbits are in fact rare, and it’s not hard to see why: they don’t do anything to spread to other machines. A wabbit, like a virus, replicates itself, but it does not have any instructions to email itself or pass itself through a computer network in order to infect other machines. The least ambitious of all malware, it is content simply to focus on utterly devastating a single machine. 

4. Trojans. Arguably the most dangerous kind of malware, at least from a social standpoint. While Trojans rarely destroy computers or even files, that’s only because they have bigger targets: your financial information, your computer’s system resources, and sometimes even massive denial-of-service attack launched by having thousands of computers all try to connect to a web server at the same time.

5. Spyware. In another instance of creative software naming, spyware is software that spies on you, often tracking your internet activities in order to serve you advertising. (Yes, it’s possible to be both adware and spyware at the same time.) 

6. Backdoors. Backdoors are much the same as Trojans or worms, except that they do something different: they open a “backdoor” onto a computer, providing a network connection for hackers or other malware to enter or for viruses or sp@m to be sent out through.

7. Exploits. Exploits attack specific security vulnerabilities. You know how Microsoft is always announcing new updates for its operating system? Often enough the updates are really trying to close the security hole targeted in a newly discovered exploit. 

8. Rootkit. The malware most likely to have a human touch, rootkits are installed by crackers (bad hackers) on other people’s computers. The rootkit is designed to camouflage itself in a system’s core processes so as to go undetected. It is the hardest of all malware to detect and therefore to remöve; many experts recommend completely wiping your hard drive and reinstalling everything fresh.

9. Keyloggers. No prïze for guessing what this software does: yes, it logs your keystrokes, i.e., what you type. Typically, the malware kind of keyloggers (as opposed to keyloggers deliberately installed by their owners to use in diagnosing computer problems) are out to log sensitive information such as passwords and financial details.

10. Dialers. Dialers dial telephone numbers via your computer’s modem. Like keyloggers, they’re only malware if you don’t want them. Dialers either dial expensive premium-rate telephone numbers, often located in small countries far from the host computer; or, they dial a hacker’s machine to transmit stolen data.

11. URL injectors. This software “injects” a given URL in place of certain URLs when you try to visit them in your browser. Usually, the injected URL is an affïliate link to the target URL. An affïliate link is a special link used to track the traffïc an affïliate (advertiser) has sent to the original website, so that the original website can pay commissions on any salës from that traffïc.

12. Adware. The least dangerous and most lucrative malware (lucrative for its distributors, that is). Adware displays ads on your computer. The Wikipedia entry on malware does not give adware its own category even though adware is commonly called malware. As Wikipedia notes, adware is often a subset of spyware. The implication is that if the user chooses to allow adware on his or her machine, it’s not really malware, which is the defense that most adware companies take. In reality, however, the choice to install adware is usually a lëgal farce involving placing a mention of the adware somewhere in the installation materials, and often only in the licensing agreement, which hardly anyone reads.

TIP: make sure that you have an updated antivirus or antispyware to avoid malwares...

By: Adnan Khalil On 06:18

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