Author: Jonas Bilinkevicius
I need to compare the file contents of a folder and its subfolders on all Win98
machines at my client's site (each machine was setup differently but, over time,
has had different patches applied to the program in question). I need to report
back only the differences found in files based upon Time/ Date stamp. Is there a
good way to do this?
Answer:
You use a recursive scanning loop (FindFirst/ FindNext/ FindClose) starting at the
topmost folder you need to examine. The loop stores each file it find into a
TStringlist. It stores a relative path to the start folder. For each file found it
also stores the searchrec.time into the Objects property of the stringlist (it uses
AddObject instead of Add). It will fit with a little typecast since it is four
bytes, like an object reference. After the end of the scan you have a list of all
files, which you can now write to disk for your reference computer to produce a
master list that will be used on the other PCs to find the differences. The output
file needs to contain the timestamp, of course, so it would be produced with
something like:
1
2 procedure SaveScan(files: TStringlist; const filename: string);
3 var
4 f: textfile;
5 i: Integer;
6 begin
7 assignfile(f, filename);
8 rewrite(f);
9 try
10 for i = 0 to files.count - 1 do
11 writeLn(f, Format('%p%s', [pointer(files.Objects[i]), files[i]]));
12 finally
13 closefile(f);
14 end;
15 end;
16
17 //Reading the list back would be:
18
19 procedure LoadScan(files: TStringlist; const filename: string);
20 var
21 f: textfile;
22 S: string;
23 begin
24 assignfile(f, filename);
25 reset(f);
26 try
27 files.clear;
28 while not EOF(f) do
29 begin
30 ReadLn(f, S);
31 files.AddObject(Copy(S, 9, Maxint), TObject(StrToInt('$' + Copy(S, 1, 8))));
32 end;
33 finally
34 Closefile(f);
35 end;
36 end;
Ok, on the other PCs you repeat the scan to build the list of files on that PC, you
load the master list into another TStringlist, sort both lists and then compare
them item by item. How complex that can get depends on what kinds of differences
you expect to find. If there can be missing and extra files in addition to changed
ones it gets a bit intricate but not too daunting. It goes like this:
You define two counters for the two lists, lets call them mi for the master list
and li for the "local" list to compare it to. Both start out at 0.
37 while (mi < masterlist.count) do
38 begin
39 if masterlist[mi] = locallist[li] then
40 begin
41 {compare the two objects properties, if not equal report the file as changed}
42 Inc(mi);
43 Inc(li);
44 end
45 else if masterlist[mi] < locallist[li] then
46 begin
47 {report masterlist[mi] as missing}
48 Inc(mi);
49 end
50 else
51 begin
52 {report locallist[li] as extra}
53 Inc(li);
54 end;
55 if mi >= masterlist.count then
56 {report any remaining files in locallist as extra}
57 if li >= locallist.count then
58 {report any remaining files in masterlist as missing and increment mi for
59 each,
60 so the loop is terminated}
61 end;
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