1 var
2   p: PChar;
3   s: string;
4 begin
5   s := 'abc';
6   p := PChar(s);   

 1 type
 2   PMyString = ^TMyString;
 3   TMyString = record
 4     buf: PAnsiChar;
 5     len: Integer;
 6     buf_len: Integer;
 7   end;
 8 
 9 // 初始化+分配空间
10 procedure string_init(var s: TMyString; buf_len: Integer);
11 begin
12   FillChar(s, SizeOf(s), 0);
13   s.buf := AllocMem(buf_len);
14   s.buf_len := buf_len;
15 end;
16 
17 // 反初始化+释放空间
18 procedure string_uninit(var s: TMyString);
19 begin
20   if s.buf_len > 0 then
21     FreeMem(s.buf);
22   FillChar(s, sizeof(s), 0);
23 end;
24 
25 // 写数据（任意数据）
26 procedure string_write(var s: TMyString; buf: Pointer; len: Integer); overload;
27 begin
28   if len + s.len > s.buf_len then
29   begin
30     Inc(s.buf_len, len * 2);
31     ReallocMem(s.buf, s.buf_len);
32   end;
33   if len > 0 then
34   begin
35     Move(buf^, (s.buf + s.len)^, len);
36     Inc(s.len, len);
37   end;
38 end;
39 
40 // 写数据（字符串数据）
41 procedure string_write(var s: TMyString; const AData: string); overload;
42 begin
43   string_write(s, PAnsiChar(AData), Length(AData) * sizeof(Char));
44 end;
45 
46 // 读数据（只针对字符串），读完后清除数据
47 function string_read(var s: TMyString): string;
48 begin
49   if s.len > 0 then
50   begin
51     SetString(Result, s.buf, s.len);
52     s.len := 0;
53   end else
54     Result := '';
55 end;

1 result := PByte(s.buf)^;
2 result := PInteger(s.buf + 1)^;
3 result := PCardinal(s.buf + 1 + 4)^;
4 result := PDouble(s.buf + 1 + 4 + 4)^;
5 result := PMsg(s.buf + 1 + 4 + 4 + 8)^.wParam;

 1 type
 2   TStr = record
 3     ptr: PChar;
 4     len: Integer;
 5   end;
 6 
 7 // 将src的数据，进行分隔，分隔出来的数据放到s中
 8 // 成功，表示分隔成功，失败表示结束
 9 function splitter(var src, s: TStr): Boolean;
10 var
11   start: PChar;
12 begin
13   result := false;
14   if src.len <= 0 then exit;
15 
16   // 1：保存原地址
17   start := src.ptr;
18   // 2: 移动到分隔字符处
19   while (src.len > 0) and not (src.ptr^ in [',', ';']) do
20   begin
21     inc(src.ptr);
22     dec(src.len);
23   end;
24   // 3: 检查分隔是否成功
25   result := src.ptr - start > 0;
26   if result then
27   begin
28     // 4: 成功，进行s赋值
29     s.ptr := start;
30     s.len := src.ptr - start;
31     // 5: 跳过分隔字符，等待下一次分隔
32     while (src.len > 0) and (src.ptr^ in [',', ';']) do
33     begin
34       inc(src.ptr);
35       dec(src.len);
36     end;
37   end;
38 end;
39 
40 function splitter_string(var src: TStr; var s: string): Boolean;
41 var
42   sub: TStr;
43 begin
44   result := splitter(src, sub);
45   if result then
46     SetString(s, sub.ptr, sub.len);
47 end;
48 
49 procedure TForm1.Button1Click(Sender: TObject);
50 var
51   src: TStr;
52   data, s: string;
53 begin
54   data := 'a,b,c';
55   src.ptr := PChar(data);
56   src.len := Length(data);
57 
58   while splitter_string(src, s) do
59     Memo1.Lines.Add('splitter: ' + s);
60 end;