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Text File  |  1998-07-30  |  7KB  |  165 lines
  1. .pn 38
  2. .fo                      Appendix C page #
  3.  
  4.                             SORT
  5.  
  6. SORTé  i≤ ß genera∞ purposσ sor⌠ utility«   I⌠ caε handlσ ver∙ ì
  7. largσ file≤ (dependinτ oε diskettσ storagσ space⌐ anΣ i≤ ablσ  ì
  8. t∩á sor⌠ oε ß recorΣ basi≤ a≤ wel∞ a≤ ß linσ basis«á   I⌠á i≤  ì
  9. no⌠á  intendeΣá t∩ bσ  ßá  gloriou≤á  all-purpose-whizz-bang-ì
  10. everything-but-the-kitchen-sinδ  sor⌠ program«   I⌠ ha≤  beeε ì
  11. pu⌠á oεá thσá deliver∙ disδ a≤ aε afterthought«á   S∩á iµá i⌠ ì
  12. doesn'⌠á fi⌠ al∞ you≥ sortinτ needs¼á kee≡  iε minΣ tha⌠á yo⌡ ì
  13. go⌠  i⌠ fo≥ free¼ anΣ don'⌠ expec⌠ ß lo⌠ oµ new-and-improved-ì
  14. better-than-eve≥ updates.
  15.  
  16. Thσá  sortinτ algorithφ employeΣ i≤ thσ onσ developeΣ  b∙á C« ì
  17. A«á R«á Hoarσá  calleΣá thσ "quicksort.ó  Fo≥ mos⌠á kind≤á oµ ì
  18. sortinτá  thi≤ i≤ thσ bes⌠ choicσ a≤ i⌠ usuall∙ ha≤ thσ  bes⌠ ì
  19. averagσ  runninτ timσ (ε loτ ε compares)«   Therσ arσ certaiε ì
  20. case≤ wherσ thσ quicksor⌠ i≤ a⌠ ß disadvantage«   Thi≤ occur≤ ì
  21. wheε  thσ  datß  t∩ bσ sorteΣ i≤  alread∙  partiall∙  sorted«  ì
  22. Iµ thσ datß i≤ alread∙ sorted¼ thσ quicksor⌠ wil∞ exhibi⌠ it≤ ì
  23. worst-casσ runninτ timσ (ε squareΣ compares)«   Kee≡ thi≤  iε ì
  24. minΣ  iµ  i⌠ seem≤ t∩ bσ takinτ aε inordinatσ amoun⌠ oµ  timσ ì
  25. oε ß nearl∙ sorteΣ file.
  26.  
  27. Thσ maximuφ amoun⌠ oµ datß tha⌠ caε bσ sorteΣ depend≤ oε  thσ ì
  28. capacit∙ oµ you≥ disk«á  T∩ determinσ ho≈ biτ ß filσ yo⌡á caε ì
  29. sort¼á  dividσá  thσá capacit∙ oµ you≥ drivσ b∙á  two«á   Fo≥ ì
  30. example¼  iµ yo⌡ havσ ß standarΣ CP/═ 2.2 systeφ anΣ ß  drivσ ì
  31. witΦ 241δ capacit∙ (remember¼  CP/═ use≤ par⌠ oµ thσ disδ fo≥ ì
  32. itselµ  anΣ  thσ  directory⌐ theε yo⌡ caε sor⌠ ß filσ  u≡  t∩ ì
  33. 241k/▓  o≥ 120δ bytes«   Thi≤ assume≤ tha⌠ yo⌡ havσ tw∩  disδ ì
  34. drives¼ onσ witΦ SORT¼ thσ othe≥ empt∙ bu⌠ fo≥ thσ filσ t∩ bσ ì
  35. sorted«   Thσ reasoε fo≥ thi≤ limitatioε i≤ becausσ SOR╘ put≤ ì
  36. it≤  temporar∙  file≤  oε thσ samσ drivσ a≤  thσ  filσ  beinτ ì
  37. sorted«   FO╥  THOS┼ O╞ YO╒ WIT╚ HAR─ DISKS║  Yes¼ therσ isé ß ì
  38. limit«á  Yo⌡á canno⌠ sor⌠ ß filσ teε megabyte≤ lonτ jus⌠á be-ì
  39. causσ yo⌡ havσ ß twent∙ megabytσ  drive«á   Sincσ  SOR╘á mus⌠ ì
  40. maintaiεá ß  filσ  contro∞ blocδ  fo≥ eacΦ temporar∙ filσá i⌠ ì
  41. generates¼á  thσ large≥  thσ sor⌠ file¼  thσ morσ temporarie≤ ì
  42. yo⌡ neeΣ and¼  consequently¼ thσ morσ memor∙ i≤ used«   I⌠ i≤ ì
  43. possiblσá tha⌠ yo⌡ coulΣ takσ u≡ al∞ oµ memor∙ jus⌠ witΦ filσ ì
  44. contro∞ blocks«ì
  45.  
  46. SOR╘á  dynamicall∙ allocate≤ spacσ accordinτ t∩ thσ  sizσá oµ  ì
  47. you≥á CP/═  system«á   Wha⌠  doe≤  thi≤  mean┐á   Well¼á  fo≥ ì
  48. starters¼ i⌠ mean≤ thσ morσ memor∙ yo⌡ have¼ thσ quicke≥ SOR╘ ì
  49. i≤á goinτá t∩á ge⌠á thσ joΓ done«á   SOR╘ use≤á mos⌠á oµá thσ ì
  50. availablσ memor∙ fo≥ thσ tex⌠ buffer¼á anΣ thσ res⌠ fo≥á FCB≤ ì
  51. anΣá recorΣá pointers«á  Thσ large≥ thσ sor⌠ buffe≥á is¼á thσ ì
  52. fewe≥  temporar∙ file≤ havσ t∩ bσ made¼  anΣ  therefore¼  thσ ì
  53. fewe≥á file≤á tha⌠ havσ t∩ bσ mergeΣ (merginτá take≤á ßá lonτ ì
  54. time).
  55.  
  56. SOR╘ ha≤ thσ abilit∙ t∩ sor⌠ no⌠ onl∙ lines¼á bu⌠ record≤á a≤  ì
  57. well«á   Thi≤á  i≤á  donσ  b∙  specifyinτ  aεá  end-of-recorΣ ìècharacte≥  (EOR)«   Thi≤ i≤ an∙ characte≥ tha⌠ signifie≤  thσ ì
  58. begin/enΣ  oµ eacΦ record«   Fo≥ instance¼  iε ß norma∞  linσ ì
  59. sort¼  thi≤ characte≥ i≤ ß linσ feeΣ (assuminτ tha⌠ eacΦ linσ ì
  60. i≤ terminateΣ b∙ ß carriagσ returε linσ feed)«   Thi≤ featurσ ì
  61. enable≤  yo⌡ t∩ sor⌠ addresses¼  financia∞ records¼  etc«   ┴ ì
  62. WOR─ O╞ WARNING«  Iµ yo⌡ havσ ß filσ iε thσ followinτ form:
  63. ì
  64. <rec 1>   Bugs Bunnyì
  65.           4242 Warner Bros. Laneì
  66.           Hollyweed, CA.  935146728ì
  67.           <EOR><CR><LF>ì
  68. <rec 2>   George Burnsì
  69.           1 Heavenly Placeì
  70.           Eternity, Timbuktu  0001ì
  71.           <EOR><CR><LF>ì
  72. <rec 3>   Afterthought Engineeringì
  73.           7266 Courtney Dr.ì
  74.           San Diego, CA.  92111ì
  75.           <EOR><CR><LF>ì
  76. ì
  77. SOR╘  wil∞  no⌠ sor⌠ i⌠ a≤ <reπ 3╛ <reπ 1╛ <reπ  2>¼  bu⌠  a≤ ì
  78. <rec3╛  <reπ  2╛ <reπ 1>«   Thi≤ i≤ becausσ record≤ ▓  anΣ  │ ì
  79. reall∙ begiε witΦ CR/LF¼  whilσ recorΣ ▒ begin≤ witΦ  "Bugs"«  ì
  80. T∩ avoiΣ this¼á yo⌡ caε d∩ onσ oµ thσ followinτá things║á (1⌐ ì
  81. begiεá thσ filσ witΦ aε enΣ oµ recorΣ characte≥ oε ß linσ al∞ ì
  82. b∙ itself¼ (2⌐ begiε thσ filσ witΦ ß blanδ line¼ o≥ (3⌐ begiε ì
  83. eacΦá recorΣá witΦá aεá enΣá oµá recorΣá characte≥áá followeΣ ì
  84. immediatel∙ b∙ thσ firs⌠ characte≥ oµ thσ nex⌠ record«  Usinτ ì
  85. thσ thirΣ methoΣ (probabl∙ thσ wors⌠ oµ thσ bunch)¼ thσ abovσ ì
  86. examplσ woulΣ looδ likσ this:
  87.  
  88. <reπ 1╛á  Bug≤ Bunn∙
  89.           424▓ Warne≥ Bros« Lanσ
  90.           Hollyweed¼áCA«  93514672╕
  91. <reπ 2╛   <EOR>Georgσ Burn≤
  92. á         ▒ Heavenl∙ Placσ
  93.           Eternity¼ Timbukt⌡  00000
  94. <reπ 3╛   <EOR>Afterthough⌠ Engineering
  95.           7266 Courtney Dr.
  96.           San Diego, CA.  92111
  97.           <EOR>
  98.  
  99. Sor⌠á i≤á no⌠ ß completel∙ barσ bone≤ sor⌠ program«á  I⌠á ha≤ ì
  100. five (well¼ four anΣ ß half⌐ options«  Thσ firs⌠ option¼ -b¼ ì
  101. allow≤á yo⌡á ski≡á leadinτ blank≤ anΣ tab≤á iεá line≤á beforσ ì
  102. comparinτ them«á  ╔ havσ n∩ ideß a⌠ thσ momen⌠ wha⌠ gooΣ thi≤ ì
  103. optioε is¼á b∙ I'φ surσ i⌠ caε bσ useΣ iε somσ way«  Thσ nex⌠ ì
  104. optioεá i≤á thσ -dé option«á  Thi≤ put≤ thσ prograφá int∩á thσ ì
  105. debuτá modσ anΣ result≤ iε ß buncΦ oµ meaningles≤ informatioε ì
  106. oεá thσ screen«á  Thσ thirΣ optioε i≤ thσá -eéá option«á  Thi≤ ì
  107. optioεá wil∞á makσ thσ prograφ promp⌠ thσ use≥ fo≥ aε enΣá oµ ì
  108. recorΣ character«á  Thσ fourtΦ optioε i≤ thσ -né option«  Thi≤ ì
  109. cause≤ thσ prograφ t∩ regarΣ thσ firs⌠ columε oµ eacΦ linσ a≤ ì
  110. ßá number«á  Thi≤á caε bσ usefu∞ iµ yo⌡ wan⌠ t∩ sor⌠á ßá filσ ì
  111. wherσá thσá firs⌠á columεá ha≤ number≤á tha⌠á arσá no⌠á righ⌠ ìèjustified«á  Iµ tw∩ number≤ arσ equal¼á thσ remainde≥ oµá thσ ì
  112. linσá i≤ sorteΣ oε aε alphabetiπ basis«á  Thσ las⌠ optioεá i≤ ì
  113. thσá -réá optioε whicΦ cause≤ thσ prograφ t∩ sor⌠á iεá reversσ ì
  114. (descending⌐ order.
  115.  
  116. All options default to off.
  117.  
  118.  
  119.                         Restrictions
  120.  
  121. 1«á Neithe≥ linσ feeΣ no≥ carriagσ returε caε bσ specifieΣ a≤ ì
  122. enΣá oµ recorΣ characters«á  Thi≤ isn'⌠ reall∙ ßá restrictioε ì
  123. sincσá usinτ carriagσ returε a≤ aε EO╥ make≤ thσ sor⌠ seeφ t∩ ì
  124. comσ ou⌠ wronτ (seσ thσ warninτ above⌐ anΣ sincσ linσ feeΣ i≤ ì
  125. the default EOR.
  126.  
  127. 2«á Thσ maximuφ recorΣ lengtΦ i≤ 51▓ bytes«á  Iµ yo⌡ wan⌠á t∩ ì
  128. sort a record longer than 512 bytes, too bad.
  129.  
  130. 3«á Wheε usinτ thσ -né option¼á thσ onl∙ lega∞ number≤ arσ thσ ì
  131. integers between -32768 and 32767.
  132.  
  133.  
  134.                          Using Sort
  135.  
  136. T∩á sor⌠á ßá tex⌠ filσ iε ascendinτ orde≥ oε ß linσá b∙á linσ ì
  137. basis, type
  138.  
  139.                sort infile outfile
  140.  
  141. wherσ infilσ i≤ thσ namσ oµ thσ inpu⌠ filσ anΣ outfilσ i≤ thσ ì
  142. namσá oµá thσá outpu⌠ file«á  Iµ yo⌡ wan⌠ t∩á ignorσá leadinτ ì
  143. blanks when sorting a file, typeì
  144.  
  145.                sort -b infile outfile
  146.  
  147. Iµ yo⌡ wan⌠ t∩ sor⌠ ß filσ wherσ yo⌡ wan⌠ thσ firs⌠ columε t∩ ì
  148. bσá regardeΣ a≤ ß columε oµ number≤ anΣ yo⌡ wan⌠ thσá number≤ ì
  149. sorted in descending (reverse) order, type
  150.  
  151.                sort -n -r infile outfile
  152.                            or
  153.                sort -nr infile outfile
  154.  
  155. Iµ yo⌡ reall∙ wan⌠ t∩ wrinτ sor⌠ ou⌠ anΣ usσ al∞ thσ options¼ ì
  156. type
  157.  
  158.                sort -bdenr infile outfile
  159.  
  160. and watch the world go by.
  161.  
  162.  
  163. Thi≤á sor⌠á prograφ wa≤ translateΣ froφá thσá Ratfo≥á versioε ì
  164. describeΣá iε "Softwarσ Toolsó b∙ Kernighaε anΣ Plauge≥ t∩á ├ ì
  165. and modified to handle dynamic buffer allocation.