procedure Button12Click(Sender: TObject);  
procedure saveNLines(filename:  string; var items: tListItems; startAt: integer; numLines: integer);

private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject); 
begin
  Form1.Caption := 'List Modify';
  ListView1.Columns.Add.Caption := '0';
  Listview1.Columns[0].Width := 300;
end;

procedure TForm1.Button12Click( Sender: TObject );
var
lines_per_block: integer;
line_index: integer;
file_number: integer;
file_extension: string;
base_filename: string;
begin
lines_per_block := strToInt( edit6.text ); // number of lines to save per file
if saveDialog1.execute then
begin
// get the file extension and everything except the extension in
// separate strings so we can inject the 1, 2, 3, ... file number.
file_extension := extractFileExt( saveDialog1.filename );
base_filename := copy( saveDialog1.filename,1,length( saveDialog1.filename ) -length( file_extension ));
// save each block of lines
line_index := 0;
file_number := 1;
while line_index < ListView1.items.count do
begin
SaveNLines(base_filename + intToStr( file_number ) + file_extension,
ListView1.items, line_index, lines_per_block);
inc( file_number );
inc( line_index, lines_per_block );
end;
end;
end;
 
procedure TForm1.saveNLines(filename: string; var items: tListItems; startAt: integer; numLines: integer);
var
sl : tStringList;
b, e : integer;
begin
  // Our temporary string list
sl := tStringList.create;
  // indices of lines to copy, inclusive
b  := startAt;
e  := startAt + numLines -1;
if e >= items.count then e := items.count -1;
  // copy the indexed lines into our temporary string list
for b := b to e do
sl.append( items.item[ b ].caption );
  // save the lines to file
sl.saveToFile( filename );
  // cleanup
sl.free
end;

  private
    { Private declarations }
    procedure saveNLines(filename: string; items: tListItems; startAt: integer; numLines: integer);
  public
    { Public declarations }
  end;

procedure TForm1.saveNLines(filename: string; items: tListItems; startAt: integer; numLines: integer);

try
  lines_per_block := strToInt( edit6.text )
except
  showMessage( 'You must specify how many lines to save per file.' );
  edit6.setFocus;
  exit
  end;
if saveDialog1.execute then ...