Removing specific lines on memo

Question

I have memo with unwanted character in lines, and I want to remove them all. Here is my code:

var
  del: Integer;
begin
  for del := 0 to m0.Lines.Count - 1 do
  begin
    if (AnsiContainsStr(m0.Lines[del], 'remove me')) then
    begin
      m0.Lines.Delete(del);
    end;
  end;
end;

With the code above still left some lines that i wanted to remove. It only delete some of them. So I tried with another approach and this is do the job.

var
  i, r, n: Integer;
begin
  for i := 0 to m0.Lines.Count - 1 do
  begin
    if (AnsiContainsStr(m0.Lines[i], 'remove me')) then
    begin
      for r := 0 to m0.Lines.Count - 1 do
      begin
        if (AnsiContainsStr(m0.Lines[r], 'remove me')) then
        begin
          for n := 0 to m0.Lines.Count - 1 do
          begin
            if (AnsiContainsStr(m0.Lines[n], 'remove me')) then
            begin
              m0.Lines.Delete(n);
            end;
          end;
          m0.Lines.Delete(r);
        end;
      end;
      m0.Lines.Delete(i);
    end;
  end;
end;

I think this is not right, and i should not do this. How to do such job elegantly ?

Answer 1

Because your loop runs from 0 to Count - 1, the line after a deleted line will be skipped.

Explanation: suppose line 3 needs to get deleted. You delete it, and now line 4 will be line 3. The loop variable i will be incremented to 4 on the next run, thus the new line 3 is never evaluated.

Solution: run your loop in reverse:

for i := m0.Lines.Count - 1 downto 0 do