magic number
1. In href="module.php?name=Lexikon&file=search&eid=1&query=source code">source code, some non-obvious constant whose value is significant to the operation of a program and that is inserted inconspicuously in-line (href="module.php?name=Lexikon&file=search&eid=1&query=hard-coded">hard-coded), rather than expanded in by a symbol set by a commented "#define". Magic numbers in this sense are bad style. 2. A number that encodes critical information used in an href="module.php?name=Lexikon&file=search&eid=1&query=algorithm">algorithm in some opaque way. The classic examples of these are the numbers used in href="module.php?name=Lexikon&file=search&eid=1&query=hash">hash or href="module.php?name=Lexikon&file=search&eid=1&query=CRC">CRC functions or the coefficients in a href="module.php?name=Lexikon&file=search&eid=1&query=linear congruential generator">linear congruential generator for href="module.php?name=Lexikon&file=search&eid=1&query=pseudo-random">pseudo-random numbers. This sense actually predates, and was ancestral to, the more common sense 1. 3. Special data located at the beginning of a href="module.php?name=Lexikon&file=search&eid=1&query=binary">binary data file to indicate its type to a utility. Under href="module.php?name=Lexikon&file=search&eid=1&query=Unix">Unix, the system and various href="module.php?name=Lexikon&file=search&eid=1&query=applications programs">applications programs (especially the href="module.php?name=Lexikon&file=search&eid=1&query=linker">linker) distinguish between types of executable file by looking for a magic number. Once upon a time, these magic numbers were href="module.php?name=Lexikon&file=search&eid=1&query=PDP-11">PDP-11 branch instructions that skipped over header data to the start of executable code 0407, for example, was href="module.php?name=Lexikon&file=search&eid=1&query=octal">octal for "branch 16 bytes relative". Nowadays only a href="module.php?name=Lexikon&file=search&eid=1&query=wizard">wizard knows the spells to create magic numbers. {MS DOS} executables begin with the magic string "MZ". *The* magic number, on the other hand, is 7+/-2. The paper cited below established the number of distinct items (such as numeric digits) that humans can hold in short-term memory. Among other things, this strongly influenced the interface design of the phone system. ["The magical number seven, plus or minus two: some limits on our capacity for processing information", George Miller, in the "Psychological Review" 63:81-97, 1956]. [href="module.php?name=Lexikon&file=search&eid=1&query=Jargon File">Jargon File] (2003-07-02) In addition suitable contents:
[ href="module.php?name=Lexikon&op=content&tid=31">2 ] [ href="module.php?name=Lexikon&op=content&tid=134">= ] [ href="module.php?name=Lexikon&op=content&tid=262">ad ] [ href="module.php?name=Lexikon&op=content&tid=396">ag ] [ href="module.php?name=Lexikon&op=content&tid=433">al ] [ href="module.php?name=Lexikon&op=content&tid=492">algorithm ] [ href="module.php?name=Lexikon&op=content&tid=544">am ] [ href="module.php?name=Lexikon&op=content&tid=592">an ] [ href="module.php?name=Lexikon&op=content&tid=683">app ] [ href="module.php?name=Lexikon&op=content&tid=700">application ] [ href="module.php?name=Lexikon&op=content&tid=738">aq ] [ href="module.php?name=Lexikon&op=content&tid=740">ar ] [ href="module.php?name=Lexikon&op=content&tid=743">arc ] [ href="module.php?name=Lexikon&op=content&tid=759">arg ] [ href="module.php?name=Lexikon&op=content&tid=800">as ] [ href="module.php?name=Lexikon&op=content&tid=822">ash ] [ href="module.php?name=Lexikon&op=content&tid=894">at ] [ href="module.php?name=Lexikon&op=content&tid=1026">b ] [ href="module.php?name=Lexikon&op=content&tid=1034">ba ] [ href="module.php?name=Lexikon&op=content&tid=1181">be ] [ href="module.php?name=Lexikon&op=content&tid=1269">bi ] [ href="module.php?name=Lexikon&op=content&tid=1298">binary ] [ href="module.php?name=Lexikon&op=content&tid=1444">bo ] [ href="module.php?name=Lexikon&op=content&tid=1535">br ] [ href="module.php?name=Lexikon&op=content&tid=1550">branch ] [ href="module.php?name=Lexikon&op=content&tid=1691">bv ] [ href="module.php?name=Lexikon&op=content&tid=1695">by ] [ href="module.php?name=Lexikon&op=content&tid=1699">byte ] [ href="module.php?name=Lexikon&op=content&tid=1708">C ] [ href="module.php?name=Lexikon&op=content&tid=1724">ca ] [ href="module.php?name=Lexikon&op=content&tid=1813">capacity ] [ href="module.php?name=Lexikon&op=content&tid=1863">cat ] [ href="module.php?name=Lexikon&op=content&tid=2001">ch ] [ href="module.php?name=Lexikon&op=content&tid=2099">ci ] [ href="module.php?name=Lexikon&op=content&tid=2138">cl ] [ href="module.php?name=Lexikon&op=content&tid=2145">class ] [ href="module.php?name=Lexikon&op=content&tid=2147">classic ] [ href="module.php?name=Lexikon&op=content&tid=2247">co ] [ href="module.php?name=Lexikon&op=content&tid=2273">code ] [ href="module.php?name=Lexikon&op=content&tid=2287">codes ] [ href="module.php?name=Lexikon&op=content&tid=2330">com ] [ href="module.php?name=Lexikon&op=content&tid=2352">comment ] [ href="module.php?name=Lexikon&op=content&tid=2545">con ] [ href="module.php?name=Lexikon&op=content&tid=2606">cons ] [ href="module.php?name=Lexikon&op=content&tid=2790">CR ] [ href="module.php?name=Lexikon&op=content&tid=2791">cr ] [ href="module.php?name=Lexikon&op=content&tid=2807">CRC ] [ href="module.php?name=Lexikon&op=content&tid=2900">cu ] [ href="module.php?name=Lexikon&op=content&tid=2976">D ] [ href="module.php?name=Lexikon&op=content&tid=3006">data ] [ href="module.php?name=Lexikon&op=content&tid=3096">date ] [ href="module.php?name=Lexikon&op=content&tid=3151">de ] [ href="module.php?name=Lexikon&op=content&tid=3304">design ] [ href="module.php?name=Lexikon&op=content&tid=3384">digit ] [ href="module.php?name=Lexikon&op=content&tid=3565">do ] [ href="module.php?name=Lexikon&op=content&tid=3623">DOS ] [ href="module.php?name=Lexikon&op=content&tid=3657">DP ] [ href="module.php?name=Lexikon&op=content&tid=3752">du ] [ href="module.php?name=Lexikon&op=content&tid=3865">ec ] [ href="module.php?name=Lexikon&op=content&tid=3896">ed ] [ href="module.php?name=Lexikon&op=content&tid=3929">ee ] [ href="module.php?name=Lexikon&op=content&tid=3946">eg ] [ href="module.php?name=Lexikon&op=content&tid=4068">encode ] [ href="module.php?name=Lexikon&op=content&tid=4148">er ] [ href="module.php?name=Lexikon&op=content&tid=4150">era ] [ href="module.php?name=Lexikon&op=content&tid=4171">es ] [ href="module.php?name=Lexikon&op=content&tid=4199">et ] [ href="module.php?name=Lexikon&op=content&tid=4279">exec ] [ href="module.php?name=Lexikon&op=content&tid=4282">executable ] [ href="module.php?name=Lexikon&op=content&tid=4497">fi ] [ href="module.php?name=Lexikon&op=content&tid=4520">file ] [ href="module.php?name=Lexikon&op=content&tid=4700">fo ] [ href="module.php?name=Lexikon&op=content&tid=4727">for ] [ href="module.php?name=Lexikon&op=content&tid=4940">function ] [ href="module.php?name=Lexikon&op=content&tid=4983">G ] [ href="module.php?name=Lexikon&op=content&tid=5057">ge ] [ href="module.php?name=Lexikon&op=content&tid=5070">gen ] [ href="module.php?name=Lexikon&op=content&tid=5141">gi ] [ href="module.php?name=Lexikon&op=content&tid=5171">gl ] [ href="module.php?name=Lexikon&op=content&tid=5205">gn ] [ href="module.php?name=Lexikon&op=content&tid=5291">gr ] [ href="module.php?name=Lexikon&op=content&tid=5390">gs ] [ href="module.php?name=Lexikon&op=content&tid=5403">gu ] [ href="module.php?name=Lexikon&op=content&tid=5434">h ] [ href="module.php?name=Lexikon&op=content&tid=5504">hard-coded ] [ href="module.php?name=Lexikon&op=content&tid=5525">hash ] [ href="module.php?name=Lexikon&op=content&tid=5540">hat ] [ href="module.php?name=Lexikon&op=content&tid=5565">header ] [ href="module.php?name=Lexikon&op=content&tid=5656">hing ] [ href="module.php?name=Lexikon&op=content&tid=5675">hm ] [ href="module.php?name=Lexikon&op=content&tid=5722">hose ] [ href="module.php?name=Lexikon&op=content&tid=5768">hr ] [ href="module.php?name=Lexikon&op=content&tid=5791">hu ] [ href="module.php?name=Lexikon&op=content&tid=5931">id ] [ href="module.php?name=Lexikon&op=content&tid=5956">ie ] [ href="module.php?name=Lexikon&op=content&tid=6013">il ] [ href="module.php?name=Lexikon&op=content&tid=6064">in ] [ href="module.php?name=Lexikon&op=content&tid=6068">inc ] [ href="module.php?name=Lexikon&op=content&tid=6194">int ] [ href="module.php?name=Lexikon&op=content&tid=6274">interface ] [ href="module.php?name=Lexikon&op=content&tid=6413">io ] [ href="module.php?name=Lexikon&op=content&tid=6482">is ] [ href="module.php?name=Lexikon&op=content&tid=6558">it ] [ href="module.php?name=Lexikon&op=content&tid=6589">J ] [ href="module.php?name=Lexikon&op=content&tid=6619">jar ] [ href="module.php?name=Lexikon&op=content&tid=6620">Jargon File ] [ href="module.php?name=Lexikon&op=content&tid=6789">ke ] [ href="module.php?name=Lexikon&op=content&tid=6822">ki ] [ href="module.php?name=Lexikon&op=content&tid=6861">kn ] [ href="module.php?name=Lexikon&op=content&tid=6918">la ] [ href="module.php?name=Lexikon&op=content&tid=7023">ld ] [ href="module.php?name=Lexikon&op=content&tid=7091">Lex ] [ href="module.php?name=Lexikon&op=content&tid=7107">li ] [ href="module.php?name=Lexikon&op=content&tid=7151">line ] [ href="module.php?name=Lexikon&op=content&tid=7176">link ] [ href="module.php?name=Lexikon&op=content&tid=7184">linker ] [ href="module.php?name=Lexikon&op=content&tid=7291">logical ] [ href="module.php?name=Lexikon&op=content&tid=7399">ls ] [ href="module.php?name=Lexikon&op=content&tid=7415">lu ] [ href="module.php?name=Lexikon&op=content&tid=7441">ly ] [ href="module.php?name=Lexikon&op=content&tid=7457">M ] [ href="module.php?name=Lexikon&op=content&tid=7463">ma ] [ href="module.php?name=Lexikon&op=content&tid=7521">magic ] [ href="module.php?name=Lexikon&op=content&tid=7582">man ] [ href="module.php?name=Lexikon&op=content&tid=7749">memory ] [ href="module.php?name=Lexikon&op=content&tid=7969">minus ] [ href="module.php?name=Lexikon&op=content&tid=8019">mm ] [ href="module.php?name=Lexikon&op=content&tid=8032">mo ] [ href="module.php?name=Lexikon&op=content&tid=8040">mod ] [ href="module.php?name=Lexikon&op=content&tid=8079">module ] [ href="module.php?name=Lexikon&op=content&tid=8167">mp ] [ href="module.php?name=Lexikon&op=content&tid=8228">ms ] [ href="module.php?name=Lexikon&op=content&tid=8382">MZ ] [ href="module.php?name=Lexikon&op=content&tid=8384">N ] [ href="module.php?name=Lexikon&op=content&tid=8386">na ] [ href="module.php?name=Lexikon&op=content&tid=8460">nc ] [ href="module.php?name=Lexikon&op=content&tid=8472">ne ] [ href="module.php?name=Lexikon&op=content&tid=8622">nf ] [ href="module.php?name=Lexikon&op=content&tid=8627">ng ] [ href="module.php?name=Lexikon&op=content&tid=8630">ni ] [ href="module.php?name=Lexikon&op=content&tid=8660">nl ] [ href="module.php?name=Lexikon&op=content&tid=8672">nn ] [ href="module.php?name=Lexikon&op=content&tid=8675">no ] [ href="module.php?name=Lexikon&op=content&tid=8760">ns ] [ href="module.php?name=Lexikon&op=content&tid=8787">nu ] [ href="module.php?name=Lexikon&op=content&tid=8799">numbers ] [ href="module.php?name=Lexikon&op=content&tid=8820">O ] [ href="module.php?name=Lexikon&op=content&tid=8910">octal ] [ href="module.php?name=Lexikon&op=content&tid=8964">om ] [ href="module.php?name=Lexikon&op=content&tid=9014">op ] [ href="module.php?name=Lexikon&op=content&tid=9120">org ] [ href="module.php?name=Lexikon&op=content&tid=9132">OS ] [ href="module.php?name=Lexikon&op=content&tid=9204">pa ] [ href="module.php?name=Lexikon&op=content&tid=9430">PD ] [ href="module.php?name=Lexikon&op=content&tid=9445">PDP ] [ href="module.php?name=Lexikon&op=content&tid=9447">PDP-11 ] [ href="module.php?name=Lexikon&op=content&tid=9457">pe ] [ href="module.php?name=Lexikon&op=content&tid=9550">ph ] [ href="module.php?name=Lexikon&op=content&tid=9651">pl ] [ href="module.php?name=Lexikon&op=content&tid=9736">plus ] [ href="module.php?name=Lexikon&op=content&tid=9908">pr ] [ href="module.php?name=Lexikon&op=content&tid=9995">process ] [ href="module.php?name=Lexikon&op=content&tid=10000">processing ] [ href="module.php?name=Lexikon&op=content&tid=10023">program ] [ href="module.php?name=Lexikon&op=content&tid=10042">programming ] [ href="module.php?name=Lexikon&op=content&tid=10125">pseudo ] [ href="module.php?name=Lexikon&op=content&tid=10253">query ] [ href="module.php?name=Lexikon&op=content&tid=10313">random ] [ href="module.php?name=Lexikon&op=content&tid=10364">rc ] [ href="module.php?name=Lexikon&op=content&tid=10385">re ] [ href="module.php?name=Lexikon&op=content&tid=10767">ro ] [ href="module.php?name=Lexikon&op=content&tid=10887">ru ] [ href="module.php?name=Lexikon&op=content&tid=10918">S ] [ href="module.php?name=Lexikon&op=content&tid=11150">se ] [ href="module.php?name=Lexikon&op=content&tid=11281">set ] [ href="module.php?name=Lexikon&op=content&tid=11314">sh ] [ href="module.php?name=Lexikon&op=content&tid=11376">si ] [ href="module.php?name=Lexikon&op=content&tid=11389">sig ] [ href="module.php?name=Lexikon&op=content&tid=11510">sk ] [ href="module.php?name=Lexikon&op=content&tid=11525">sl ] [ href="module.php?name=Lexikon&op=content&tid=11651">so ] [ href="module.php?name=Lexikon&op=content&tid=11745">source ] [ href="module.php?name=Lexikon&op=content&tid=11746">source code ] [ href="module.php?name=Lexikon&op=content&tid=11789">Spec ] [ href="module.php?name=Lexikon&op=content&tid=11790">spec ] [ href="module.php?name=Lexikon&op=content&tid=11825">spell ] [ href="module.php?name=Lexikon&op=content&tid=11934">st ] [ href="module.php?name=Lexikon&op=content&tid=12093">string ] [ href="module.php?name=Lexikon&op=content&tid=12109">struct ] [ href="module.php?name=Lexikon&op=content&tid=12133">su ] [ href="module.php?name=Lexikon&op=content&tid=12246">sy ] [ href="module.php?name=Lexikon&op=content&tid=12312">system ] [ href="module.php?name=Lexikon&op=content&tid=12359">T ] [ href="module.php?name=Lexikon&op=content&tid=12369">table ] [ href="module.php?name=Lexikon&op=content&tid=12416">tar ] [ href="module.php?name=Lexikon&op=content&tid=12588">th ] [ href="module.php?name=Lexikon&op=content&tid=12721">to ] [ href="module.php?name=Lexikon&op=content&tid=12787">tr ] [ href="module.php?name=Lexikon&op=content&tid=12873">tron ] [ href="module.php?name=Lexikon&op=content&tid=12939">tw ] [ href="module.php?name=Lexikon&op=content&tid=12970">type ] [ href="module.php?name=Lexikon&op=content&tid=12986">ua ] [ href="module.php?name=Lexikon&op=content&tid=13030">um ] [ href="module.php?name=Lexikon&op=content&tid=13146">up ] [ href="module.php?name=Lexikon&op=content&tid=13175">us ] [ href="module.php?name=Lexikon&op=content&tid=13252">va ] [ href="module.php?name=Lexikon&op=content&tid=13260">value ] [ href="module.php?name=Lexikon&op=content&tid=13274">var ] [ href="module.php?name=Lexikon&op=content&tid=13310">ve ] [ href="module.php?name=Lexikon&op=content&tid=13366">vi ] [ href="module.php?name=Lexikon&op=content&tid=13794">wizard ] [ href="module.php?name=Lexikon&op=content&tid=13877">ws ] [ href="module.php?name=Lexikon&op=content&tid=14075">yt ] [ href="module.php?name=Lexikon&op=content&tid=14079">Z ] [ href="module.php?name=Lexikon&op=content&tid=14088">za ]
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