write specific line in tmemo according to line number - delphi

Question

I am using the following to insert text from a text file into TMemo.
procedure TForm1.Button1Click(Sender: TObject);
var
SL: TStringList;
begin
SL := TStringList.Create;
try
SL.LoadFromFile('c:\testimeng\keyfil.txt');
Memo1.Lines.Assign(SL);
finally
SL.Free;
end;
end;
What i want to know is how to add a single line according to row number to TMemo when i choose the specific row number.
Example output:
During this time he has distinguished himself in the academic, sporting and cultural spheres of school life.
During this time he has distinguished himself in the academic and sporting spheres of school life.
During this time he has distinguished himself in the academic and cultural spheres of school life.
During this time he has distinguished himself in the academic aspect of school life.
During this time he has distinguished himself in both the sporting and cultural aspects of school life.
Any help appreciated.

Answer 1

I think you're asking about putting a single line from the TStringList into the TMemo when you specify which item (index, or line number) from the TStringList. If that's the case, you can use something like this:
Memo1.Lines.Add(SL[Index]);
So if the first line in your keyfile.txt is
During this time he has distinguished himself in the academic, sporting and cultural spheres of school life.
You would use
Memo1.Lines.Add(SL[0]); // Desired line number - 1
Ok, after your comment to your question, I think I know what you're wanting to do. Here's one way to do it:
Drop a TListBox, a TButton, and a TMemo on your form. I arranged mine with the ListBox on the left, the button next to it (at the top right corner), and then the memo just to the right of the button.
In the FormCreate event, populate the TListBox with your text file and clear the existing memo content:
procedure TForm1.FormCreate(Sender: TObject);
begin
Memo1.Clear;
ListBox1.Items.LoadFromFile('c:\testimeng\keyfil.txt');
end;
Double-click the button to add an OnClick handler:
procedure TForm1.Button1Click(Sender: TObject);
var
s: string;
begin
// If there's an item selected in the listbox...
if ListBox1.ItemIndex <> -1 then
begin
// Get the selected item
s := ListBox1.Items[ListBox1.ItemIndex];
// See if it's already in the memo. If it's not, add it at the end.
if Memo1.Lines.IndexOf(s) = -1 then
Memo1.Lines.Add(s);
end;
end;
Now run the app. Click on an item in the listbox, and then click the button. If the item is not already present in the memo, it will be added as a new last line. If it's already there, it won't be added (to prevent duplicates).
If you're wanting to add it to the end of the current last line (extending the paragraph, perhaps), then you'd do it like this:
// Add selected sentence to the end of the last line of the memo,
// separating it with a space from the content that's there.
Memo1.Lines[Memo1.Lines.Count - 1] := Memo1.Lines[Memo1.Lines.Count - 1] + #32 + s;
So, it should be clear by now that to add to the end of a specific line, you just grab the content that's already
there and add to it. For instance, if the user types 3 into a TEdit:
procedure TForm1.FormCreate(Sender: TObject);
begin
SL := TStringList.Create;
SL.LoadFromFile('c:\testimeng\keyfil.txt');
end;
procedure TForm1.ButtonAddTextClick(Sender: TObject);
var
TheLine: Integer;
begin
// SL is the TStringList from the FormCreate code above
TheLine := StrToIntDef(Edit1.Text, -1);
if (TheLine > -1) and (TheLine < Memo1.Lines.Count) then
if TheLine < SL.Count then
Memo1.Lines[TheLine] := Memo1.Lines[TheLine] + SL[TheLine];
end;

Answer 2

Write a specific line with String by Mouse Clicking on TMemo
Procedure TForm1.Button1Click(Sender: TObject);
Var SL: TStringList;
LineNumber : Integer;
Begin
LineNumber := Memo1.Perform(EM_LINEFROMCHAR, Memo1.SelStart, 0);
Memo1.SelStart := Memo1.Perform(EM_LINEINDEX, LineNumber, 0);
Memo1.SelLength := Length(Memo1.Lines[LineNumber]) ;
Memo1.SetFocus;
SL := TStringList.Create;
try
SL.LoadFromFile('c:\testimeng\keyfil.txt');
Memo1.SelText := SL.Strings[0];
finally
SL.Free;
end;
End;