///写一个文本文件
procedure TForm1.Button1Click(Sender: TObject);
var
s:TStrings;
begin
s:=TStringList.Create;
s.Add('AAAAAAAAAAAA');
s.Add('BBBBBBBBBBBB');
s.Add('CCCCCCCCCCCC');
s.SaveToFile('d:/temp.txt');
s.free;
end;
///将文本文件第二行第三个字符改为 A
procedure TForm1.Button2Click(Sender: TObject);
var
s:TStrings;
m,n:integer;
ss:string;
begin
m:=2;
n:=3;
s:=TStringList.Create;
s.LoadFromFile('d:/temp.txt');
if (m>s.Count) or (length(widestring(s[m-1]))<n) then
showmessage('行或列太大')
else
begin
ss:=widestring(s[m-1]);
ss[n]:='A';
s[m-1]:=ss;
s.SaveToFile('d:/temp.txt');
end;
s.free;
end;
