Author: Jonas Bilinkevicius

I am writing an adventure game and need to store information in a save game. The 
game requires data from 3 different records and one variable

record1 = hotspot scene information(50 recs),
record2 = conversation information (60 recs),
record3 = hypertext information(50 recs)
variable = integer - # of scene currently on.

My problem is that I need to seek for a particular record of particular type in the 
file (I do not want to have to keep huge arrays of records in memory). I know how 
to do this with a file containing records of only one record type but have no clue 
how to combine all three records and one integer into a single random access file.

Answer:

I generally use a file with a header, then just keep the header in memory and use 
it to seek to the records I need.

1   type
2     TSaveHeader = record
3       scene: Integer;
4       hotspots: LongInt;
5       talk: LongInt;
6       hype: LongInt;
7     end;
8   
9   var
10    SaveHeader: TSaveHeader;
11  
12  procedure OpenSaveFile(fname: string);
13  var
14    f: file;
15    i: Integer;
16  begin
17    AssignFile(f, fname);
18    Reset(f, 1);
19    BlockRead(f, SaveHeader, Sizeof(TSaveHeader));
20    { get one set of records }
21    Seek(f, SaveHeader.hotspots);
22    for i := 1 to 50 do
23      BlockRead(f, somevar, sizeof_hotspotrec);
24    { and so on }
25    CloseFile(f);
26  end;
27  
28  { assuming the file is open }
29  
30  procedure GetHotspotRec(index: LongInt; var hotspotrec: THotspot);
31  var
32    offset: LongInt;
33  begin
34    offset := SaveHeader.hotspots + index * Sizeof(THotSpot);
35    Seek(f, offset);
36    BlockRead(f, hotspotrec, Sizeof(THotspot));
37  end;