Blockread from file and display items.

[Guthro]

This is a bit of a noobie question but here goes.
I want to use Blockread to find a file and then display its contents. Using the D5 example, it uses an OpenDialog and the SaveDialog. Fine, but how do I display fields from with the file. The output can be a memo, Grid or whatever.
It's been ages since I used Delphi so be gentle

What I'm trying to do is read a file that has an inventory of items which are seperated with I believe null characters. It looks much like a flat file. I can now read the first item by reading each single letter from Buf and concatenating it and then assiging it to an editbox text. But whatever I do I can't go beyond the first item.

Is there a simple way to open a file, examine it's contents and then list the English text and ignore all the spurious characters ?

 

[buho]

If you are reading from a buffer which have zeroes and sending the data to a text-oriented object (like TEdit or TMemo), you need to skip the zeroes.

If you want to keep the line structure in a TMemo, replace the zeroes with #13#10 (if the data lacks them).

Basically, if any char is lesser than #32 (SPACE) and is not #9 (TAB), #13 (CR) or #10 (LF); you need to skip/replace it too.

buho (A).

 

[Guthro]

How would I do that ?
Does BlockRead read the whole file including the spaces or does it need code to ignore the unwanted characters at the time of reading ?

 

[buho]

BlockRead care nothing about characters. It will read everything.


Say you are doing a BlockRead(MyFile, @MyBuffer, 1024) and the file stiil have at least 1024 bytes to read; BlockRead will read exactly 1024 bytes, no more no less, paying no attention to the values, neither skipping nor adding anything. Pure binary read.

type 
  TMyBuffer = array[1..1024] of char;
var  
  MyBuffer : TMyBuffer;
  i        : integer;

// We have a file opened somewhere and a TMemo ready to be used
// Error checking needed in the read
BlockRead(MyFile, @MyBuffer, 1024);

for i = 1 to 1024 do
  if (MyBuffer[i] < #23) and not (MyBuff[i] in [#9, #10, #13])
    then MyMemo.Text := MyMemo.Text + MyBuff[i];

The code above will get a clean copy of the block in a TMemo, without zeroes or control chars. If the file have not CRLF (#13#10) as delimiters, you will get a continous stream of chars with no line breaks.

To break down lines in a file using zeroes as line delimiters, do something like:

const
  Filtered = [#1..#23] - [#9, #10, #13];

// Skip is filtered
// Send CRLF if zero
// Send char otherwise
for i = 1 to 1024 do
  if not (MyBuffer[i] in Filtered)
    then if MyBuffer[i] = #0
      then MyMemo.Text := MyMemo.Text + #13#10
      else MyMemo.Text := MyMemo.Text + MyBuff[i];

buho (A).