自写的LastPos，寻找字符串里的最后一个字符，RTL里没有提供这个函数——Delphi的String下标是从1开始的

function LastPos(strFind :string; ch: Char): integer;
var
    i, n: integer;
begin
    Result := -1;
    if strFind=‘‘ then
    begin
        Exit;
    end;
    for i:=0 to Length(strFind) do
    begin
        if strFind[i]=ch then
            Result := i;
    end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  s1: String;
begin
  s1 := ‘abc‘;
  ShowMessage(s1[1]);
  ShowMessage(IntToStr(Length(‘/myaccount/save1/‘)));
  ShowMessage(IntToStr(LastPos(‘/myaccount/save1/‘, ‘/‘)));
end;

function LastPos(const S: string; C: Char): Integer;
var
    i: Integer;
begin
    i := Length(S);
    while (i > 0) and (S[i] <> C) do
        Dec(i);
    Result := i;
end;