CP/M/CPM_CDROM.iso/mbug/mbug003.arc/PASCAL.008

Text File | 1979-12-31 | 8KB | 190 lines

                    PASCAL   FOR   BASIC   PROGRAMMERS

                               Dixon Kenney

                                 PART VIII

    Iεá thi≤á article¼á wσá arσá goinτ t∩ adΣ ß ne≈á procedurσá t∩á ou≥ ì
Inventor∙ program«á  Thi≤ prograφ wil∞ lis⌠ al∞ thσ item≤ oµ ou≥á database«  ì
Iε orde≥ t∩ usσ thσ databasσ later¼á wσ arσ als∩ goinτ t∩ adΣ anothe≥ fielΣ ì
t∩ thσ record¼ s∩ tha⌠ i⌠ wil∞ no≈ looδ likσ thi≤ -

áááááááááááááá  PartReπ ╜ Record
áááááááááááááá    PartNuφ      ║ 100░ .« 9999;
áááááááááááááá    Descriptioε  ║ St20;
áááááááááááááá    Cos⌠         ║ Real;
áááááááááááááá    Retai∞       ║ Real;
áááááááááááááá    MinO╚        ║ Integer;
áááááááááááááá    MaxReorde≥   ║ Integer;
áááááááááááááá    CurrentO╚    ║ Integer;
áááááááááááááá    DeleteΣ      ║ Boolean;
áááááááááááááá End;

Thσá ne≈ fielΣ i≤ thσ las⌠ one¼á whicΦ wil∞ bσ useΣ t∩ marδ ß recorΣ iµá wσ ì
wan⌠á t∩á deletσ i⌠ froφ thσ database«á  A⌠ datß entry¼á i⌠ wil∞ bσ se⌠á t∩ ì
false«  T∩ d∩ this¼ alte≥ thσ listinτ oµ "NEWITEM.PROó t∩ looδ likσ thi≤ -

        GoToXY(32,11); Read(MaxReorder);
        GoTOXY(32,13); Read(CurrentOH);
        Deleted := False;
        Write(PartFile, Part)
    End;

The addition is the line which sets the field "Deleted" to False.

     Herσá i≤á thσ listinτ fo≥ thσ procedurσ whicΦ list≤ al∞ thσá item≤á oµ ì
stocδ oε thσ screeε :

áááááProcedurσ Listem;

áááááConst
ááááá  Heade≥      ╜ º ¬ LISTIN╟ O╞ AL╠ ITEM╙ O╞ STOC╦ ¬ ';
ááááá  ScreenLine≤ ╜ 15;

áááááVar
ááááá  YesN∩       ║ Char;
ááááá  Ro≈         ║ Integer;

áááááBegin

ááááá  Assign(PartFile,FileName);
ááááá  Reset(PartFile);

ááááá  ClrScr;
ááááá  Writeln(º ':20¼ Header);
ááááá  Write('Iteφ #':6,º       Description':22,º    Cost':10);
ááááá  Writeln(º  Retail':10,'Minimum':8,'Maximum':8,'Oε Hand':8);
ááááá  Writeln;

ááááá  Ro≈ :╜ 0;èááááá  Whilσ no⌠ EOF(PartFile⌐ do
ááááá    Begin
ááááá    Read(PartFile,Part);
ááááá    WitΦ Par⌠ do
ááááá      Begin
ááááá      Write(PartNum:6,Description:22,Cost:10:2,Retail:10:2);
ááááá      Writeln(MinOH:8,MaxReorder:8,CurrentOH:8);
ááááá      Ro≈ :╜ Succ(Row);

ááááá      Iµ Ro≈ ╜ ScreenLine≤ then
ááááá        Begin
ááááá          Writeln;
ááááá          Write('Pres≤ <RETURN> t∩ continue');
ááááá          Readln(YesNo);
ááááá          Ro≈ :╜ 0
ááááá      EnΣ     √ oµ Iµ Ro≈ }
ááááá    EnΣ       √ oµ WitΦ Par⌠ D∩ }
ááááá  End╗        √ oµ Whilσ No⌠ EO╞ }

ááááá  Close(PartFile);

ááááá  Writeln;
ááááá  Write('Typσá <RETURN╛á ke∙á wheε yo⌡ havσá finisheΣá witΦá thi≤ ì
ááááádispla∙ ');
ááááá  Readln(YesNo);

áááááEnd╗           √ oµ Procedurσ Listeφ }

The skeleton of this procedure looks like this -

1    Open the File, and put the record pointer to zero.
2    Clear the Screen, and write the column headers on it.
3    a    Get a record from the disk
     b    Write it to the screen
     c    If the screen is full ( by calculation a fixed number
          of records, called ScreenLines ), pause until the
          user presses a key.
4    When the file is fully listed, wait until the user types
     a key, and then return to the Main Menu.

Comments on this procedure -

                      While Not EOF(Partfile) do

    Thi≤ forma⌠ create≤ ß loop«á  Thi≤ i≤ onσ oµ thσ │ type≤ oµ loopinτ ì
o≥ repetitivσ statement≤ availablσ iε Pascal«á  Wσ havσ seeε thσ othe≥á tw∩ ì
alread∙ - thσ 'FO╥ ° :╜ bottoφ t∩ to≡ doº type¼á anΣ thσ 'REPEA╘ .«á UNTILº  ì
type«  Thi≤ presen⌠ typσ ha≤ thσ format

          While < condition > do [ Begin .... End ]

    Thσá conditioεá i≤ evaluateΣ a⌠ thσ beginninτ oµá thσá loop«á  Thi≤ ì
mean≤á tha⌠á thσ loo≡ ma∙ no⌠ bσ executeΣ a⌠ all¼á sincσ thσ conditioεá ma∙ ì
turε ou⌠ t∩ bσ falsσ beforσ thσ loo≡ i≤ entered« Thσ blocδ i≤ markeΣ b∙ thσ ì
usua∞ Begiε anΣ EnΣ iµ morσ thaε onσ statemen⌠ i≤ presen⌠ iε it.



è     Thσá functioε EOF(filevariable⌐ i≤ ß Booleaε function¼á whicΦá return≤ ì
thσ valuσ TRU┼ iµ thσ recorΣ pointe≥ i≤ a⌠ thσ EO╞ marker¼á beyonΣ thσ las⌠ ì
componen⌠á oµ thσ filσ itself«á  S∩ "Whilσ no⌠ EOF(..)ó mean≤ "executσá thσ ì
blocδá whilσ thσ recorΣ pointe≥ stil∞ point≤ t∩ ß recorΣ iε thσá file¼á anΣ ì
sto≡ a≤ sooε a≤ i⌠ read≤ thσ EO╞ marke≥ a⌠ thσ enΣ oµ thσ file."

                          Write ( ... :m:n )

    Wheεá yo⌡ arσ writinτ something¼á yo⌡ caε definσ thσ widtΦá oµá thσ ì
fielΣá t∩á writσ i⌠ iε b∙ addinτ ß coloε anΣ aε intege≥ whicΦá define≤á thσ ì
numbe≥á oµ characte≥ space≤ i⌠ wil∞ takσ up«á  Thi≤ ":mó ma∙ bσ appendeΣ t∩ ì
eithe≥ ß variablσ labe∞ o≥ ß string¼ a≤ yo⌡ seσ we'vσ donσ here¼ firstl∙ iε ì
thσá columε headers¼á anΣ secondl∙ iε thσ actua∞ recorΣ contents«á  Iµá thσ ì
numbe≥ whicΦ i≤ beinτ printeΣ i≤ ß rea∞ number¼á theε yo⌡ caε adΣ ßá seconΣ ì
fielΣ widtΦ number¼ a≤ wσ havσ donσ fo≥ Cos⌠ anΣ Retai∞ here¼ whicΦ define≤ ì
thσ numbe≥ oµ column≤ useΣ fo≥ decima∞ fractioε digits«á  S∩ herσ Cos⌠ wil∞ ì
bσá iε ß fielΣ 1░ characte≥ space≤ wide¼á tw∩ oµ whicΦ wil∞ bσ useΣ fo≥ thσ ì
decima∞á fractioεá digit≤ ¿ thσ cent≤ )¼á anΣ onσ fo≥á thσá decima∞á point¼ ì
leavinτ ╖ fo≥ thσ actua∞ intege≥ numbe≥ ¿ thσ dollar≤ ).

                           Row := Succ(Row)

    Thσá functioεá Succ(x⌐á return≤á thσá valuσá whicΦá thσá T╨á manua∞ ì
describe≤á a≤ thσ "successoró oµ x¼á iµ i⌠ exists«á  ° mus⌠ bσ oµ ßá scala≥ ì
type«  Here¼ ° i≤ aε integer«  Iµ ° ha≤ thσ valuσ oµ 1¼ it≤ successo≥ i≤ 2«  ì
Iε fact¼á wσ havσ herσ aε alternativσ t∩ ° :╜ ° ½ 1«á  Bu⌠ thσ functioε caε ì
bσ useΣ iε an∙ scala≥ type¼ excep⌠ REAL.

     Iµá thσá typσ Weeδ wa≤ ß scala≥ typσ defineΣ a≤á thσá value≤á (Monday¼ ì
Tuesday¼á Wednesday¼ Thursday¼ Friday¼ Saturday¼ Sunday)¼ theε Succ(Monday⌐ ì
i≤ Tuesday.

                         If Row = ScreenLines

    Thi≤á littlσá blocδ simpl∙ count≤ thσ numbe≥ oµ record≤ printeΣá oε ì
thσ screen¼á and¼ wheε tha⌠ numbe≥ equal≤ ß predefineΣ number¼ halt≤ outpu⌠ ì
unti∞ thσ use≥ presse≤ thσ returε key«

áááááááááUser≤ oµ dBAS┼ I╔ wil∞ bσ familia≥ witΦ thi≤ littlσ ì
ááááááááápiecσá oµ politeness¼áiε thσ "Waitinτ .«á ó messagσ ì
áááááááááwheε yo⌡ DISPLA┘ AL╠ record≤ iε ß file«á  I⌠á mean≤ ì
ááááááááátha⌠ thσ use≥ caε reaΣ thσ displa∙ witΦ ease¼ rath-ì
áááááááááe≥á thaε havinτ i⌠ scrol∞ u≡ thσ screeε a⌠ ßá speeΣ ì
ááááááááátoo fast for him to read.

    Yo⌡ wil∞ noticσ witΦ thi≤ listinτ tha⌠ thσ screeε displa∙ doe≤á no⌠ ì
indicatσ whethe≥ o≥ no⌠ ß recorΣ ha≤ beeε markeΣ fo≥ deletion«  Tha⌠ littlσ ì
good∙ wil∞ come¼á bu⌠ we'vσ reserveΣ i⌠ fo≥ thσ nex⌠ procedure¼á whicΦ wil∞ ì
finΣ ß particula≥ item¼ anΣ displa∙ i⌠ nicel∙ oε thσ screen.

     Wσ wil∞ neeΣ t∩ adΣ t∩ thσ INVENT.PA╙ codσ thσ followinτ changes

     a) in the Menu array contents

          MenuList[9] := ' 8 : List on screen all items of stock');

     b) in the 'Case Item of' block

          8 : Listem;è     Somσá peoplσ havσ askeΣ mσ t∩ recommenΣ ß gooΣ Pasca∞ tex⌠á book«á Thσ ì
onσá ╔ havσ founΣ mos⌠ helpfu∞ i≤ Koffman'≤ "Probleφ Solvinτ anΣ StructureΣ ì
Programminτá iε Pascal"¼á publisheΣ b∙ Addison-Wesley«á  I⌠ i≤ writteεá fo≥ ì
Pasca∞ oε ß largσ computer¼á anΣ somσ oµ thσ nicσ function≤ whicΦ appea≥ iε ì
TurboPasca∞á - fo≥á example¼á thσ String[▌ definition≤ - d∩ no⌠á appea≥á iε ì
these¼á generall∙ older¼á versions«  Thσ booδ assume≤ tha⌠ al∞ strinτ inpu⌠ ì
wil∞á bσá deal⌠ witΦ oε ß character-by-characte≥ basis¼á rathe≥ thaεá oεá ß ì
characte≥ strinτ basis¼á a≤ wσ caε iε Turb∩ Pascal«á  Nonetheless¼ thσ booδ ì
certainl∙ explain≤ thing≤ iε ß ver∙ clea≥ way«á  TurboPasca∞ i≤ ver∙á closσ ì
t∩ UCS─ Pascal¼á s∩ book≤ writteε abou⌠ tha⌠ dialec⌠ oµ thσ languagσ ma∙ bσ ì
oµ use¼á althougΦ al∞ text≤ wil∞ bσ oµ somσ help¼ a≤ thσ basiπ structurσ oµ ì
Pasca∞ i≤ thσ same¼ n∩ matte≥ wha⌠ thσ dia-lec⌠ chosen«  Thσ variou≤ Pasca∞ ì
dialect≤á arσá certainl∙á morσ closel∙ relateΣ t∩ eacΦ othe≥ thaεá arσá thσ ì
variou≤ Basiπ dialects«

                            END OF PART EIGHT.