PChar 类型的又一些用法

//使用 PChar^
var
  p: PChar;
begin
  p := PChar('abcd');
  ShowMessage(p);    {abcd}
  ShowMessage(p^);   {a}
  p := p + 2;
  ShowMessage(p^);   {c}
  Dec(p);
  ShowMessage(p^);   {b}
  ShowMessage(p);    {bcd}
end;


//遍历 PChar 中的字符
var
  p: PChar;
begin
  p := PChar('abcd');
  while p^ <> #0 do
  begin
    ShowMessage(p^); {分别显示: a、b、c、d}
    Inc(p);
  end;
end;


//替代缓冲区与内存分配的简单方法
var
  p: PChar;
begin
  p := PChar(StringOfChar(#0, 255));
  GetWindowsDirectory(p, 255); {譬如获取 Windows 目录}
  ShowMessage(p);              {C:\WINDOWS}
end;