Handling Files in Delphi

There are two ways to read from a file:

• Line by line
• Reading the entire contents into a string list.

Line by line

To read the file line by line we need to open the file for input by calling the reset procedure:

var
  Afile : TextFile;
  buffer : string;
begin
  AssignFile(Afile, 'notes.txt') ;

try
  Reset(Afile);
  ReadLn(Afile, buffer) ;
  Memo2.Lines.Add(buffer) ;

finally
  CloseFile(Afile) ;
end; 

end;

There are two types of read procedures, readln and read. The difference is that Readln moves to the pointer to the next line after reading and Read does not. Here's how you would read from a file using Read procedure:

var
  Afile : TextFile;
  buffer : string
begin
  AssignFile(Afile, 'notes.txt') ;

try
  Reset(Afile);
  Read(Afile, buffer) ;
  Memo2.Lines.Add(buffer) ;

finally
  CloseFile(Afile) ;
end; 

end;

Reading the entire contents of a file

Double click on the "read from file" button and add the following code:

procedure TForm1.Button2Click(Sender: TObject);
begin
Memo2.Lines.LoadFromFile('notes.txt');
end;

We use tmemo's loadfromfile() procedure to load the entire contents of a file.