如何读取这样的文件？(50分)

使用如下方法创建了一个二进制文件。
var
fs: TStream;
Str: Pchar;
begin
str := Pchar('Hello, 你好！'); //<=====看清楚,不是String
fs := TFileStream.Create('D:/File.txt', fmCreate);
try
fs.Write(str, Length(str) + 1);
finally
fs.Free;
end;
end;

问题来了，如何才能从此文件中读取出原来的字符串？

var
fs: TStream;
Str: Pchar;
begin
fs := TFileStream.Create('D:/File.txt', fmOpenRead);
try
fs.position := 0;
fs.Read(str, fs.size);
finally
fs.Free;
end;
end;

To japhe
想当然吧？ 还未给　Strchar分配存储空间呢。
其实问题的关键在：读它出来，可以在Memo或richedit中正常显示出来。

Memo1.Lines.LoadFromFile('c:/yourfile.txt');

各位别急，问题没有这么简单。麻烦运行一下代码，用记事本打开File.txt看一下：是乱码的。

来自：Demogodyou, 时间：2006-4-30 12:43:41, ID：3431756
To japhe
想当然吧？ 还未给　Strchar分配存储空间呢。
其实问题的关键在：读它出来，可以在Memo或richedit中正常显示出来。

不错，上面我写的那段代码确实是想当然，但是，搂主有没有测试过，
读出来后，Str确实是'Hello, 你好！'

不妨设置断点监视一下看看。

已设断点查看，是乱码。

procedure TForm1.btn1Click(Sender: TObject);
var
S:TStream;
Pchar;
begin
P:=PChar('Hello');
S:=TFileStream.Create('File.txt',fmCreate);
try
S.Write(P,Length(P));
finally
FreeAndNil(S);
end;
end;

procedure TForm1.btn2Click(Sender: TObject);
var
S:TStream;
PChar;
begin
S:=TFileStream.Create('File.txt',fmOpenRead);
try
P:=AllocMem(S.Size);
S.ReadBuffer(P,S.Size);
Caption:=P;
finally
FreeAndNil(S);
FreeMem(P);//读出来了，但这里释放出错
end;
end;
占个位学习

Demogodyou写的好像没什么问题吧，在memo中显示也没什么问题。
var
fs: TStream;
Str: Pchar;
begin
fs := TFileStream.Create('c:/vx.txt', fmOpenRead);
try
fs.Read(str, fs.Size);
ShowMessage(str);
Memo1.Text := StrPas(Str);
finally
fs.Free;
end;
end;

OK做出来了：
procedure TForm1.btn1Click(Sender: TObject);
var
S:TStream;
Pchar;
begin
P:=PChar('Hello');
S:=TFileStream.Create('File.txt',fmCreate);
try
S.Write(P^,Length(P));//这里存入5字节，不带最后的#0
finally
FreeAndNil(S);
end;
end;

procedure TForm1.btn2Click(Sender: TObject);
var
S:TStream;
PChar;
begin
S:=TFileStream.Create('File.txt',fmOpenRead);
try
P:=AllocMem(S.Size+1);//这里分配了6字节，都是#0
S.ReadBuffer(P^,S.Size);//这里读入了5字节，第6字节是#0
Caption:=P;
finally
FreeAndNil(S);
FreeMem(P);
end;
end;

其实是想达到这样一个目的：使用某个方法将纯文本保存为一个二进制文件，就是用记事本打开是乱码那种，以达到隐藏信息的功能。然后再从此文件中把原来的字符串读出来使用(可以在memo或richedit中正常显示)。

你的这句是错的：
fs.Write(str, Length(str) + 1);
str是一个指针(型如Integer变量)，写入文件的就不是str指向的内存区了
要加一个“^”
fs.Write(str^, Length(str) + 1);

那就直接用blockread,blockwrite方法，不用流文件也行。

感谢liuchong,
换个问法吧，其实我想知道如何将纯文本以二进制形式保存到文件中(在记事本中打开是乱码那种，主要想隐藏信息)，然后再把原来的字符串从文件中读出来使用。

将字符串加密吧，记事本读取文件的代码不知怎么写的
猜测一下：记事本也是读入二进制数据，分析ASCII码，解码成字符的
不管用FileStream或BlockWrite写入的数据，只是把一个内存块的数据写入了
这个内存块还是array of Char型的(string或PChar也相当于array of Char)，只要这个内存块是原始数据，没有加密，写入时，也是踏踏实实的写入的，只有加密写入才是正道啊

加密就是了，比如Base64等。为什么一定要搞什么二进制啊？

多谢各位！难道非要加密不成？

DES加密函数：


unit Des;

interface

uses
SysUtils;

type
TKeyByte = array[0..5] of Byte;
TDesMode = (dmEncry, dmDecry);

function EncryStr(Str, Key: String): String;
function DecryStr(Str, Key: String): String;
function EncryStrHex(Str, Key: String): String;
function DecryStrHex(StrHex, Key: String): String;

const
BitIP: array[0..63] of Byte = //初始值置IP
(57, 49, 41, 33, 25, 17, 9, 1,
59, 51, 43, 35, 27, 19, 11, 3,
61, 53, 45, 37, 29, 21, 13, 5,
63, 55, 47, 39, 31, 23, 15, 7,
56, 48, 40, 32, 24, 16, 8, 0,
58, 50, 42, 34, 26, 18, 10, 2,
60, 52, 44, 36, 28, 20, 12, 4,
62, 54, 46, 38, 30, 22, 14, 6 );

BitCP: array[0..63] of Byte = //逆初始置IP-1
( 39, 7, 47, 15, 55, 23, 63, 31,
38, 6, 46, 14, 54, 22, 62, 30,
37, 5, 45, 13, 53, 21, 61, 29,
36, 4, 44, 12, 52, 20, 60, 28,
35, 3, 43, 11, 51, 19, 59, 27,
34, 2, 42, 10, 50, 18, 58, 26,
33, 1, 41, 9, 49, 17, 57, 25,
32, 0, 40, 8, 48, 16, 56, 24 );

BitExp: array[0..47] of Integer = // 位选择函数E
( 31, 0, 1, 2, 3, 4, 3, 4, 5, 6, 7, 8, 7, 8, 9,10,
11,12,11,12,13,14,15,16,15,16,17,18,19,20,19,20,
21,22,23,24,23,24,25,26,27,28,27,28,29,30,31,0 );

BitPM: array[0..31] of Byte = //置换函数P
( 15, 6,19,20,28,11,27,16, 0,14,22,25, 4,17,30, 9,
1, 7,23,13,31,26, 2, 8,18,12,29, 5,21,10, 3,24 );

sBox: array[0..7] of array[0..63] of Byte = //S盒
( ( 14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7,
0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8,
4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0,
15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13 ),

( 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10,
3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,
0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,
13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9 ),

( 10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8,
13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,
13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,
1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12 ),

( 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,
13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,
10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,
3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14 ),

( 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,
14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,
4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,
11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3 ),

( 12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,
10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,
9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,
4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13 ),

( 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,
13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,
1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,
6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12 ),

( 13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,
1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,
7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,
2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11 ) );

BitPMC1: array[0..55] of Byte = //选择置换PC-1
( 56, 48, 40, 32, 24, 16, 8,
0, 57, 49, 41, 33, 25, 17,
9, 1, 58, 50, 42, 34, 26,
18, 10, 2, 59, 51, 43, 35,
62, 54, 46, 38, 30, 22, 14,
6, 61, 53, 45, 37, 29, 21,
13, 5, 60, 52, 44, 36, 28,
20, 12, 4, 27, 19, 11, 3 );

BitPMC2: array[0..47] of Byte =//选择置换PC-2
( 13, 16, 10, 23, 0, 4,
2, 27, 14, 5, 20, 9,
22, 18, 11, 3, 25, 7,
15, 6, 26, 19, 12, 1,
40, 51, 30, 36, 46, 54,
29, 39, 50, 44, 32, 47,
43, 48, 38, 55, 33, 52,
45, 41, 49, 35, 28, 31 );

var
subKey: array[0..15] of TKeyByte;

implementation

procedure initPermutation(var inData: array of Byte);
var
newData: array[0..7] of Byte;
i: Integer;
begin
FillChar(newData, 8, 0);
for i := 0 to 63 do
if (inData[BitIP shr 3] and (1 shl (7- (BitIP and $07)))) <> 0 then
newData[i shr 3] := newData[i shr 3] or (1 shl (7-(i and $07)));
for i := 0 to 7 do inData := newData;
end;

procedure conversePermutation(var inData: array of Byte);
var
newData: array[0..7] of Byte;
i: Integer;
begin
FillChar(newData, 8, 0);
for i := 0 to 63 do
if (inData[BitCP shr 3] and (1 shl (7-(BitCP and $07)))) <> 0 then
newData[i shr 3] := newData[i shr 3] or (1 shl (7-(i and $07)));
for i := 0 to 7 do inData := newData;
end;

procedure expand(inData: array of Byte; var outData: array of Byte);
var
i: Integer;
begin
FillChar(outData, 6, 0);
for i := 0 to 47 do
if (inData[BitExp shr 3] and (1 shl (7-(BitExp and $07)))) <> 0 then
outData[i shr 3] := outData[i shr 3] or (1 shl (7-(i and $07)));
end;

procedure permutation(var inData: array of Byte);
var
newData: array[0..3] of Byte;
i: Integer;
begin
FillChar(newData, 4, 0);
for i := 0 to 31 do
if (inData[BitPM shr 3] and (1 shl (7-(BitPM and $07)))) <> 0 then
newData[i shr 3] := newData[i shr 3] or (1 shl (7-(i and $07)));
for i := 0 to 3 do inData := newData;
end;

function si(s,inByte: Byte): Byte;
var
c: Byte;
begin
c := (inByte and $20) or ((inByte and $1e) shr 1) or
((inByte and $01) shl 4);
Result := (sBox[c] and $0f);
end;

procedure permutationChoose1(inData: array of Byte;
var outData: array of Byte);
var
i: Integer;
begin
FillChar(outData, 7, 0);
for i := 0 to 55 do
if (inData[BitPMC1 shr 3] and (1 shl (7-(BitPMC1 and $07)))) <> 0 then
outData[i shr 3] := outData[i shr 3] or (1 shl (7-(i and $07)));
end;

procedure permutationChoose2(inData: array of Byte;
var outData: array of Byte);
var
i: Integer;
begin
FillChar(outData, 6, 0);
for i := 0 to 47 do
if (inData[BitPMC2 shr 3] and (1 shl (7-(BitPMC2 and $07)))) <> 0 then
outData[i shr 3] := outData[i shr 3] or (1 shl (7-(i and $07)));
end;

procedure cycleMove(var inData: array of Byte; bitMove: Byte);
var
i: Integer;
begin
for i := 0 to bitMove - 1 do
begin
inData[0] := (inData[0] shl 1) or (inData[1] shr 7);
inData[1] := (inData[1] shl 1) or (inData[2] shr 7);
inData[2] := (inData[2] shl 1) or (inData[3] shr 7);
inData[3] := (inData[3] shl 1) or ((inData[0] and $10) shr 4);
inData[0] := (inData[0] and $0f);
end;
end;

procedure makeKey(inKey: array of Byte; var outKey: array of TKeyByte);
const
bitDisplace: array[0..15] of Byte =
( 1,1,2,2, 2,2,2,2, 1,2,2,2, 2,2,2,1 );
var
outData56: array[0..6] of Byte;
key28l: array[0..3] of Byte;
key28r: array[0..3] of Byte;
key56o: array[0..6] of Byte;
i: Integer;
begin
permutationChoose1(inKey, outData56);

key28l[0] := outData56[0] shr 4;
key28l[1] := (outData56[0] shl 4) or (outData56[1] shr 4);
key28l[2] := (outData56[1] shl 4) or (outData56[2] shr 4);
key28l[3] := (outData56[2] shl 4) or (outData56[3] shr 4);
key28r[0] := outData56[3] and $0f;
key28r[1] := outData56[4];
key28r[2] := outData56[5];
key28r[3] := outData56[6];

for i := 0 to 15 do
begin
cycleMove(key28l, bitDisplace);
cycleMove(key28r, bitDisplace);
key56o[0] := (key28l[0] shl 4) or (key28l[1] shr 4);
key56o[1] := (key28l[1] shl 4) or (key28l[2] shr 4);
key56o[2] := (key28l[2] shl 4) or (key28l[3] shr 4);
key56o[3] := (key28l[3] shl 4) or (key28r[0]);
key56o[4] := key28r[1];
key56o[5] := key28r[2];
key56o[6] := key28r[3];
permutationChoose2(key56o, outKey);
end;
end;

procedure encry(inData, subKey: array of Byte;
var outData: array of Byte);
var
outBuf: array[0..5] of Byte;
buf: array[0..7] of Byte;
i: Integer;
begin
expand(inData, outBuf);
for i := 0 to 5 do outBuf := outBuf xor subKey;
buf[0] := outBuf[0] shr 2;
buf[1] := ((outBuf[0] and $03) shl 4) or (outBuf[1] shr 4);
buf[2] := ((outBuf[1] and $0f) shl 2) or (outBuf[2] shr 6);
buf[3] := outBuf[2] and $3f;
buf[4] := outBuf[3] shr 2;
buf[5] := ((outBuf[3] and $03) shl 4) or (outBuf[4] shr 4);
buf[6] := ((outBuf[4] and $0f) shl 2) or (outBuf[5] shr 6);
buf[7] := outBuf[5] and $3f;
for i := 0 to 7 do buf := si(i, buf);
for i := 0 to 3 do outBuf := (buf[i*2] shl 4) or buf[i*2+1];
permutation(outBuf);
for i := 0 to 3 do outData := outBuf;
end;

procedure desData(desMode: TDesMode;
inData: array of Byte; var outData: array of Byte);
// inData, outData 都为8Bytes，否则出错
var
i, j: Integer;
temp, buf: array[0..3] of Byte;
begin
for i := 0 to 7 do outData := inData;
initPermutation(outData);
if desMode = dmEncry then
begin
for i := 0 to 15 do
begin
for j := 0 to 3 do temp[j] := outData[j]; //temp = Ln
for j := 0 to 3 do outData[j] := outData[j + 4]; //Ln+1 = Rn
encry(outData, subKey, buf); //Rn ==Kn==> buf
for j := 0 to 3 do outData[j + 4] := temp[j] xor buf[j]; //Rn+1 = Ln^buf
end;

for j := 0 to 3 do temp[j] := outData[j + 4];
for j := 0 to 3 do outData[j + 4] := outData[j];
for j := 0 to 3 do outData[j] := temp[j];
end
else if desMode = dmDecry then
begin
for i := 15 downto 0 do
begin
for j := 0 to 3 do temp[j] := outData[j];
for j := 0 to 3 do outData[j] := outData[j + 4];
encry(outData, subKey, buf);
for j := 0 to 3 do outData[j + 4] := temp[j] xor buf[j];
end;
for j := 0 to 3 do temp[j] := outData[j + 4];
for j := 0 to 3 do outData[j + 4] := outData[j];
for j := 0 to 3 do outData[j] := temp[j];
end;
conversePermutation(outData);
end;

//////////////////////////////////////////////////////////////

function EncryStr(Str, Key: String): String;
var
StrByte, OutByte, KeyByte: array[0..7] of Byte;
StrResult: String;
I, J: Integer;
begin
if (Length(Str) > 0) and (Ord(Str[Length(Str)]) = 0) then
raise Exception.Create('Error: the last char is NULL char.');
if Length(Key) < 8 then
while Length(Key) < 8 do Key := Key + Chr(0);
while Length(Str) mod 8 <> 0 do Str := Str + Chr(0);

for J := 0 to 7 do KeyByte[J] := Ord(Key[J + 1]);
makeKey(keyByte, subKey);

StrResult := '';

for I := 0 to Length(Str) div 8 - 1 do
begin
for J := 0 to 7 do
StrByte[J] := Ord(Str[I * 8 + J + 1]);
desData(dmEncry, StrByte, OutByte);
for J := 0 to 7 do
StrResult := StrResult + Chr(OutByte[J]);
end;

Result := StrResult;
end;

function DecryStr(Str, Key: String): String;
var
StrByte, OutByte, KeyByte: array[0..7] of Byte;
StrResult: String;
I, J: Integer;
begin
if Length(Key) < 8 then
while Length(Key) < 8 do Key := Key + Chr(0);

for J := 0 to 7 do KeyByte[J] := Ord(Key[J + 1]);
makeKey(keyByte, subKey);

StrResult := '';

for I := 0 to Length(Str) div 8 - 1 do
begin
for J := 0 to 7 do StrByte[J] := Ord(Str[I * 8 + J + 1]);
desData(dmDecry, StrByte, OutByte);
for J := 0 to 7 do
StrResult := StrResult + Chr(OutByte[J]);
end;
while (Length(StrResult) > 0) and
(Ord(StrResult[Length(StrResult)]) = 0) do
Delete(StrResult, Length(StrResult), 1);
Result := StrResult;
end;

///////////////////////////////////////////////////////////

function EncryStrHex(Str, Key: String): String;
var
StrResult, TempResult, Temp: String;
I: Integer;
begin
TempResult := EncryStr(Str, Key);
StrResult := '';
for I := 0 to Length(TempResult) - 1 do
begin
Temp := Format('%x', [Ord(TempResult[I + 1])]);
if Length(Temp) = 1 then Temp := '0' + Temp;
StrResult := StrResult + Temp;
end;
Result := StrResult;
end;

function DecryStrHex(StrHex, Key: String): String;
function HexToInt(Hex: String): Integer;
var
I, Res: Integer;
ch: Char;
begin
Res := 0;
for I := 0 to Length(Hex) - 1 do
begin
ch := Hex[I + 1];
if (ch >= '0') and (ch <= '9') then
Res := Res * 16 + Ord(ch) - Ord('0')
else if (ch >= 'A') and (ch <= 'F') then
Res := Res * 16 + Ord(ch) - Ord('A') + 10
else if (ch >= 'a') and (ch <= 'f') then
Res := Res * 16 + Ord(ch) - Ord('a') + 10
else raise Exception.Create('Error: not a Hex String');
end;
Result := Res;
end;

var
Str, Temp: String;
I: Integer;
begin
Str := '';
for I := 0 to Length(StrHex) div 2 - 1 do
begin
Temp := Copy(StrHex, I * 2 + 1, 2);
Str := Str + Chr(HexToInt(Temp));
end;
Result := DecryStr(Str, Key);
end;

//这里的Str表示你要进行加密的字符串，Key表示密钥；
//function EncryStrHex(Str, Key: String): String;

//这里的Str表示你要进行解密的字符串，Key表示密钥；
//function DecryStrHex(StrHex, Key: String): String;

end.

多谢各位，看来只好加解密。