Delphi Basics : Append command

DelphiBasics

Append
Procedure

Open a text file to allow appending of text to the end

System unit

procedure Append(var FileHandle TextFile);

Description

The Append procedure opens a file given by FileHandle to allow subsequent writes to append to the end of the file.

You must use AssignFile to assign a file to the FileHandle before using Append.

This is often used when logging information - existing log data must be preserved, with the new log information appended to the end.

Use Write or WriteLn to write to the file after this Append is executed.

Related commands

AssignFile		Assigns a file handle to a binary or text file
TextFile		Declares a file type for storing lines of text
Write		Write data to a binary or text file
WriteLn		Write a complete line of data to a text file

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Example code : Appending a line of text to an existing file

var
  myFile : TextFile;
  text   : string;

begin
  // Try to open the Test.txt file for writing to
  AssignFile(myFile, 'Test.txt');
  ReWrite(myFile);

  // Write a couple of well known words to this file
  WriteLn(myFile, 'Hello');
  WriteLn(myFile, 'World');

  // Close the file
  CloseFile(myFile);

  // Reopen to append a final line to the file
  Append(myFile);

  // Write this final line
  WriteLn(myFile, 'Final line added');

  // Close the file
  CloseFile(myFile);

  // Reopen the file for reading
  Reset(myFile);

  // Display the file contents
  while not Eof(myFile) do
  begin
    ReadLn(myFile, text);
    ShowMessage(text);
  end;

  // Close the file for the last time
  CloseFile(myFile);
end;

Show full unit code

  Hello
  World
  Final line added