The Basics of C Programming" The previous discussion becomes a little clearer if you understand how memory addresses work in a computer's hardware. If you have not read it already, now would be a good time to read How Bits and Bytes Work to fully understand bits, bytes and words. All computers have memory, also known as RAM (random access memory). For example, your computer might have 16 or 32 or 64 megabytes of RAM installed right now. float f; This statement says, "Declare a location named f that can hold one floating point value." While you think of the variable f, the computer thinks of a specific address in memory (for example, 248,440). f = 3.14; The compiler might translate that into, "Load the value 3.14 into memory location 248,440." There are, by the way, several interesting side effects to the way your computer treats memory. int i, s[4], t[4], u=0; for (i=0; i<=4; i++) { s[i] = i; t[i] =i; } printf("s:t\n"); for (i=0; i<=4; i++) printf("%d:%d\n", s[i], t[i]); printf("u = %d\n", u); s[1000000] = 5;
This Awesome Urn Will Turn You into a Tree After You Die | Design for Good You don't find many designers working in the funeral business thinking about more creative ways for you to leave this world (and maybe they should be). However, the product designer Gerard Moline has combined the romantic notion of life after death with an eco solution to the dirty business of the actual, you know, transition. His Bios Urn is a biodegradable urn made from coconut shell, compacted peat and cellulose and inside it contains the seed of a tree. Once your remains have been placed into the urn, it can be planted and then the seed germinates and begins to grow. I, personally, would much rather leave behind a tree than a tombstone. Editor's Note: The Bios Urn is a patented design of Estudimoline, the design company of Gerard Moline, a Catalan artist and product designer who designed Bio Urn for animals in 1999.
Malicious Linux Commands - From (This article was originally published in Ubuntu Forums but was removed there. Ubuntuguide feels that knowledge about these risks is more important than any misguided attempts to "protect the public" by hiding their potential dangers or protect the (K)Ubuntu/Linux image. The original article has therefore been re-created (and subsequently edited) here.) ATTENTION: It is worthwhile to have some basic awareness about malicious commands in Linux. It is also worthwhile to always enable a Kubuntu screensaver or Ubuntu screensaver with a password so that a casual passerby is not able to maliciously execute one of these commands from your keyboard while you are away from your computer. When in doubt as to the safety of a recommended procedure or command, it is best to verify the command's function from several sources, such as from readily available documentation on Linux commands (e.g. manpages). Here are some common examples of dangerous commands that should raise a red flag. rm -r In Perl
An Overview of Cryptography As an aside, the AES selection process managed by NIST was very public. A similar project, the New European Schemes for Signatures, Integrity and Encryption (NESSIE), was designed as an independent project meant to augment the work of NIST by putting out an open call for new cryptographic primitives. NESSIE ran from about 2000-2003. While several new algorithms were found during the NESSIE process, no new stream cipher survived cryptanalysis. CAST-128/256: CAST-128, described in Request for Comments (RFC) 2144, is a DES-like substitution-permutation crypto algorithm, employing a 128-bit key operating on a 64-bit block. A digression: Who invented PKC? 3.3. Let me reiterate that hashes are one-way encryption. Hash algorithms that are in common use today include: Message Digest (MD) algorithms: A series of byte-oriented algorithms that produce a 128-bit hash value from an arbitrary-length message. A digression on hash collisions.
Would Wiretapping Laws Spell the End of Quantum Encryption?: Scientific American The nascent industry of quantum communications could suffer a fatal blow if the U.S. enacts sweeping new regulations to provide wiretapping access to law enforcement. The weirdness of quantum mechanics makes it possible for two parties to share an encryption key and be sure that no one else can copy it. Any attempt to eavesdrop on the communication of the quantum key would irreversibly disturb its quantum state, thus revealing that the channel is being wiretapped. In recent decades, the development of quantum communication and encryption has motivated significant advances in basic research in mathematics, physics and engineering. The first of such futuristic systems are already commercially available and have been installed by a few banks and government agencies. The New York Times now reports that the U.S. government is seeking to establish new regulations that would outlaw encryption systems that don’t provide a built-in way for a third party to intercept and decrypt the data.
Introduction to Algorithms - Download free content from MIT What is a Digital Signature? Bob has been given two keys. One of Bob's keys is called a Public Key, the other is called a Private Key. Bob's Public key is available to anyone who needs it, but he keeps his Private Key to himself. Susan (shown below) can encrypt a message using Bob's Public Key. With his private key and the right software, Bob can put digital signatures on documents and other data. Bob's software then encrypts the message digest with his private key. Finally, Bob's software appends the digital signature to document. Bob now passes the document on to Pat. Plot complication... It just so happens that Susan works at the company's certificate authority center. Now Bob's co-workers can check Bob's trusted certificate to make sure that his public key truly belongs to him. Let's say that Bob sends a signed document to Pat. Pat's software then takes Bob's public key from the certificate and uses it to check Bob's signature. Warning: You may be missing a few lines of text if you print this document.
Learn how to throw lethal playing cards - The Blogs at HowStuffWorks If you watch the following video, you will be able to see one of the world’s leading card-throwing experts practicing his craft. With a business card and a flick of his wrist he can pop balloons, extinguish candles, hit targets, etc. Around the 50-second point, you will also see him impale a tomato with a business card. Around 3:15, Rick Smith demonstrates his technique very quickly. How to throw cards fast and effectively !!!!! See also: If you need a source of cheap playing cards, check out the dollar store – two decks for a buck. One level up from card throwing is knife throwing: - the fastest knife thrower in the world - How to throw knives [[[Jump to previous How To - How to blow your money if you are super-wealthy]]]
PC Architecture. A book by Michael B. Karbo - a book by Michael Karbo. This book is protected by copyright. It has been published in many European countries but never in English language. Therefore I desided to upload it to the Internet. It is free to use as it is for personal, non-commercial use. All rights belong to Michael Karbo. These web pages have been produced from a Microsoft Word file. PC Architecture.
The Hello World Collection Airplane Travel Tips - 100 Words or Less - Gadling Don't take sleep aids until you're in the air - Airplane tip by Melanie Linn Gutowski (RSS feed) on Aug 9th, 2010 at 11:16AM Though it may seem appealing to sleep through those long waits on the tarmac, avoid the temptation to take a sleep aid until you're up in the air. You may miss important announcements, or, worse yet, you may be asked to disembark and wait for a later plane. If you plan to take a sleep aid, be sure to take a seat where you are less likely to block in other passengers, like a window seat or a middle seat. [Photo: Flickr | mirjoran] Swap shelves in airport bookstores - Airplane tip by Erin Frank (RSS feed) on Aug 9th, 2010 at 10:16AM I've been noticing swap shelves in airport bookstores lately. A few airports, like Portland International, have used bookstores where someone has undoubtedly just sold back that bestseller you wanted, and you can pick it up for less than full price. [Photo: Flickr | jrodmanjr] Wear sunglasses during the flight - Airplane tip by Staci M. Hi.
Dictionary of Algorithms and Data Structures This web site is hosted by the Software and Systems Division, Information Technology Laboratory, NIST. Development of this dictionary started in 1998 under the editorship of Paul E. Black. After 20 years, DADS needs to move. This is a dictionary of algorithms, algorithmic techniques, data structures, archetypal problems, and related definitions. Don't use this site to cheat. Currently we do not include algorithms particular to business data processing, communications, operating systems or distributed algorithms, programming languages, AI, graphics, or numerical analysis: it is tough enough covering "general" algorithms and data structures. Some terms with a leading variable, such as n-way, m-dimensional, or p-branching, are under k-. To look up words or phrases, enter them in the box, then click the button. We thank those who contributed definitions as well as many others who offered suggestions and corrections. Here are some references on algorithms and data structures. Bibliography
Signs that you're a bad programmer - Software Engineering Tips Why was this written? Most of these faults were discovered the hard way by the author himself, either because he committed them himself or saw them in the work of others. This paper is not meant for grading programmers, it was intended to be read by programmers who trust their ability to judge when something is a sign of bad practice, and when it's a consequence of special circumstances. This paper was written to force its author to think, and published because he thinks you lot would probably get a kick out of it, too. 1. Inability to reason about code Reasoning about code means being able to follow the execution path ("running the program in your head") while knowing what the goal of the code is. Symptoms Remedies To get over this deficiency a programmer can practice by using the IDE's own debugger as an aide, if it has the ability to step through the code one line at a time. 2. Object Oriented Programming is an example of a language model, as is Functional or Declarative programming. 3. 4.
Human World Human World The women of the Tiwi tribe in the South Pacific are married at birth. When Albert Einstein died, his final words died with him. St Patrick, the patron saint of Ireland, was not Irish. The lance ceased to be an official battle weapon in the British Army in 1927. St. Many sailors used to wear gold earrings so that they could afford a proper burial when they died. Some very Orthodox Jew refuse to speak Hebrew, believing it to be a language reserved only for the Prophets. A South African monkey was once awarded a medal and promoted to the rank of corporal during World War I. Born 4 January 1838, General Tom Thumb's growth slowed at the age of 6 months, at 5 years he was signed to the circus by P.T. Because they had no proper rubbish disposal system, the streets of ancient Mesopotamia became literally knee-deep in rubbish. The Toltecs, Seventh-century native Mexicans, went into battle with wooden swords so as not to kill their enemies. Pogonophobia is the fear of beards. John D.