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Elephant In Cairo
An elephant in Cairo is a term used in computer programming to describe a piece of data that matches the search criteria purposefully inserted at the end of a search space, in order to make sure the search algorithm terminates; it is a humorous example of a sentinel value. The term derives from a humorous essay circulated on the Internet that was published in ''Byte'' magazine on September 1989, describing how various professions would go about hunting elephants. Algorithm When hunting elephants, the article describes programmers as following this algorithm: :# Go to Africa. :# Start at the Cape of Good Hope.The Cape of Good Hope has been traditionally believed to be Africa's southernmost point, but that is actually Cape Agulhas''. :# Work northward in an orderly manner, traversing the continent alternately east and west, :# During each traverse pass: :#:* Catch each animal seen. :#:* Compare each animal caught to a known elephant. :#:* Stop when a match is detected. This algorith ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Programming
Computer programming is the process of performing a particular computation (or more generally, accomplishing a specific computing result), usually by designing and building an executable computer program. Programming involves tasks such as analysis, generating algorithms, profiling algorithms' accuracy and resource consumption, and the implementation of algorithms (usually in a chosen programming language, commonly referred to as coding). The source code of a program is written in one or more languages that are intelligible to programmers, rather than machine code, which is directly executed by the central processing unit. The purpose of programming is to find a sequence of instructions that will automate the performance of a task (which can be as complex as an operating system) on a computer, often for solving a given problem. Proficient programming thus usually requires expertise in several different subjects, including knowledge of the application domain, specialized algori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sentinel Value
In computer programming, a sentinel value (also referred to as a flag value, trip value, rogue value, signal value, or dummy data) is a special value in the context of an algorithm which uses its presence as a condition of termination, typically in a loop or recursive algorithm. The sentinel value is a form of in-band data that makes it possible to detect the end of the data when no out-of-band data (such as an explicit size indication) is provided. The value should be selected in such a way that it is guaranteed to be distinct from all legal data values since otherwise, the presence of such values would prematurely signal the end of the data (the semipredicate problem). A sentinel value is sometimes known as an "Elephant in Cairo," due to a joke where this is used as a physical sentinel. In safe languages, most sentinel values could be replaced with option types, which enforce explicit handling of the exceptional case. Examples Some examples of common sentinel values and their us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet
The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies. The Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web (WWW), electronic mail, telephony, and file sharing. The origins of the Internet date back to the development of packet switching and research commissioned by the United States Department of Defense in the 1960s to enable time-sharing of computers. The primary precursor network, the ARPANET, initially served as a backbone for interconnection of regional academic and military networks in the 1970s to enable resource shari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Byte (magazine)
''Byte'' (stylized as ''BYTE'') was a microcomputer magazine, influential in the late 1970s and throughout the 1980s because of its wide-ranging editorial coverage. "''Byte'' magazine, the leading publication serving the homebrew market ..." ''Byte'' started in 1975, shortly after the first personal computers appeared as kits advertised in the back of electronics magazines. ''Byte'' was published monthly, with an initial yearly subscription price of $10. Whereas many magazines were dedicated to specific systems or the home or business users' perspective, ''Byte'' covered developments in the entire field of "small computers and software", and sometimes other computing fields such as supercomputers and high-reliability computing. Coverage was in-depth with much technical detail, rather than user-oriented. The company was purchased by McGraw-Hill in 1979, a watershed event that led to the rapid purchase of many of the early computer magazines by larger publishers. By this time t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area.Sayre, April Pulley (1999), ''Africa'', Twenty-First Century Books. . With billion people as of , it accounts for about of the world's human population. Africa's population is the youngest amongst all the continents; the median age in 2012 was 19.7, when the worldwide median age was 30.4. Despite a wide range of natural resources, Africa is the least wealthy continent per capita and second-least wealthy by total wealth, behind Oceania. Scholars have attributed this to different factors including geography, climate, tribalism, colonialism, the Cold War, neocolonialism, lack of democracy, and corruption. Despite this low concentration of wealth, recent economic expansion and the large and young population make Afr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cape Of Good Hope
The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is the southern tip of Africa, based on the misbelief that the Cape was the dividing point between the Atlantic and Indian oceans, and have nothing to do with north or south. In fact, by looking at a map, the southernmost point of Africa is Cape Agulhas about to the east-southeast. The currents of the two oceans meet at the point where the warm-water Agulhas current meets the cold-water Benguela current and turns back on itself. That oceanic meeting point fluctuates between Cape Agulhas and Cape Point (about east of the Cape of Good Hope). When following the western side of the African coastline from the equator, however, the Cape of Good Hope marks the point where a ship begins to travel more eastward than southward. Thus, the first mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cape Agulhas
Cape Agulhas (; pt, Cabo das Agulhas , "Cape of the Needles") is a rocky headland in Western Cape, South Africa. It is the geographic southern tip of the African continent and the beginning of the dividing line between the Atlantic and Indian Oceans according to the International Hydrographic Organization. Historically, the cape has been known to sailors as a major hazard on the traditional clipper route. It is sometimes regarded as one of the great capes. It was most commonly known in English as Cape L'Agulhas until the 20th century. The town of L'Agulhas is located near to the cape. Geography Cape Agulhas is located in the Overberg region, 170 kilometres (105 mi) southeast of Cape Town. The cape was named by Portuguese navigators, who called it ''Cabo das Agulhas''—Portuguese for "Cape of Needles"—after noticing that around the year 1500 the direction of magnetic north (and therefore the compass needle) coincided with true north in the region. The cape is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bounds Checking
In computer programming, bounds checking is any method of detecting whether a variable is within some bounds before it is used. It is usually used to ensure that a number fits into a given type (range checking), or that a variable being used as an array index is within the bounds of the array (index checking). A failed bounds check usually results in the generation of some sort of exception signal. Because performing bounds checking during every usage is time-consuming, it is not always done. Bounds-checking elimination is a compiler optimization technique that eliminates unneeded bounds checking. Range checking A range check is a check to make sure a number is within a certain range; for example, to ensure that a value about to be assigned to a 16-bit integer is within the capacity of a 16-bit integer (i.e. checking against wrap-around). This is not quite the same as type checking. Other range checks may be more restrictive; for example, a variable to hold the number of a cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abnormal Termination
An abnormal end or abend is an abnormal termination of software, or a program crash. This usage derives from an error message from the IBM OS/360, IBM zOS operating systems. Usually capitalized, but may appear as "abend". Some common ABEND codes are ABEND 0C7 (data exception) and ABEND 0CB (division by zero).List of ABEND codes on madisoncollege.edu Abends can be "soft" (allowing automatic recovery) or "hard" (terminating the activity). page 352 Errors or crashes on the Novell NetWare network operating system are usually called ABENDs. Communities of NetWare administrators sprung up around the Internet, such a [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drowning
Drowning is a type of suffocation induced by the submersion of the mouth and nose in a liquid. Most instances of fatal drowning occur alone or in situations where others present are either unaware of the victim's situation or unable to offer assistance. After successful resuscitation, drowning victims may experience breathing problems, vomiting, confusion, or unconsciousness. Occasionally, victims may not begin experiencing these symptoms until several hours after they are rescued. An incident of drowning can also cause further complications for victims due to low body temperature, aspiration of vomit, or acute respiratory distress syndrome (respiratory failure from lung inflammation.). Drowning is more likely to happen when spending extended periods of time near large bodies of water. Risk factors for drowning include alcohol use, drug use, epilepsy, minimal swim training or a complete lack of training, and, in the case of children, a lack of supervision. Common drowning ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cairo
Cairo ( ; ar, القاهرة, al-Qāhirah, ) is the capital of Egypt and its largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metropolitan area, with a population of 21.9 million, is the 12th-largest in the world by population. Cairo is associated with ancient Egypt, as the Giza pyramid complex and the ancient cities of Memphis and Heliopolis are located in its geographical area. Located near the Nile Delta, the city first developed as Fustat, a settlement founded after the Muslim conquest of Egypt in 640 next to an existing ancient Roman fortress, Babylon. Under the Fatimid dynasty a new city, ''al-Qāhirah'', was founded nearby in 969. It later superseded Fustat as the main urban centre during the Ayyubid and Mamluk periods (12th–16th centuries). Cairo has long been a centre of the region's political and cultural life, and is titled "the city of a thousand m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elephant Test
The duck test is a form of abductive reasoning, usually expressed as "If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck." The test implies that a person can identify an unknown subject by observing that subject's habitual characteristics. It is sometimes used to counter abstruse arguments that something is not what it appears to be. History The French automaton maker Jacques de Vaucanson created a mechanical duck in 1738. The mechanical duck would quack, move its head to eat grain which it would appear to digest, and after a short time would excrete a mixture that looked and smelled like duck droppings. The irony is that while the phrase is often cited as proof of abductive reasoning, it is not proof, as the mechanical duck is still not a living duck. In popular culture Douglas Adams parodied this test in his book ''Dirk Gently's Holistic Detective Agency'': Monty Python also referenced the test in the Witch Logic scene i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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