delphi中字符串和16进制数据之间如何转换

delphi中字符串和16进制数据之间怎么转换?
怎么把一个字符串转换成16进制数据,然后再把16进制数转成字符串?

[解决办法]
unit BinHexTools;

interface
function HexToBin(HexNr : string): string; //把十六进制字符串转换为二进制字符串
function HexCharToInt(HexToken : char):Integer; //转换一个十六进制字符为整数
function HexCharToBin(HexToken : char): string;//转换一个十六进制字符为二进制字符串
function pow(base, power: integer): integer;//指数函数
function BinStrToInt(BinStr : string) : integer;//把二进制字符串转换为整数
function DecodeSMS7Bit(PDU : string):string;// 解码一个7-bit SMS (GSM 03.38) 为ASCII码
function ReverseStr(SourceStr : string) : string; //反转一个字符串

implementation
uses sysutils, dialogs; 

function HexCharToInt(HexToken : char):Integer; 
begin 
{if HexToken>#97 then HexToken:=Chr(Ord(HexToken)-32); 
{ use lowercase aswell }

Result:=0;
if (HexToken>#47) and (HexToken<#58) then { chars 0....9 }
Result:=Ord(HexToken)-48
else if (HexToken>#64) and (HexToken<#71) then { chars A....F }
Result:=Ord(HexToken)-65 + 10;
end;

function HexCharToBin(HexToken : char): string;
var DivLeft : integer;
begin
DivLeft:=HexCharToInt(HexToken); { first HEX->BIN }
Result:='';
{ Use reverse dividing }
repeat { Trick; divide by 2 }
if odd(DivLeft) then { result = odd ? then bit = 1 }
Result:='1'+Result { result = even ? then bit = 0 }
else
Result:='0'+Result;
DivLeft:=DivLeft div 2; { keep dividing till 0 left and length = 4 }
until (DivLeft=0) and (length(Result)=4); { 1 token = nibble = 4 bits }
end;

function HexToBin(HexNr : string): string; 
{ only stringsize is limit of binnr } 
var Counter : integer; 
begin
Result:=''; 

for Counter:=1 to length(HexNr) do
Result:=Result+HexCharToBin(HexNr[Counter]);
end;

function pow(base, power: integer): integer; 
var counter : integer; 
begin 
Result:=1; 

for counter:=1 to power do 
Result:=Result*base; 
end; 

function BinStrToInt(BinStr : string) : integer; 
var counter : integer; 
begin 
if length(BinStr)>16 then 
raise ERangeError.Create(#13+BinStr+#13+ 
'is not within the valid range of a 16 bit binary.'+#13); 

Result:=0; 

for counter:=1 to length(BinStr) do 
if BinStr[Counter]='1' then 
Result:=Result+pow(2,length(BinStr)-counter); 
end; 

function DecodeSMS7Bit(PDU : string):string; 
var OctetStr : string; 
OctetBin : string; 
Charbin : string; 
PrevOctet: string; 
Counter : integer; 
Counter2 : integer; 
begin 
PrevOctet:=''; 
Result:=''; 

for Counter:=1 to length(PDU) do 
begin 
if length(PrevOctet)>=7 then { if 7 Bit overflow on previous } 
begin 
if BinStrToInt(PrevOctet)<>0 then 
Result:=Result+Chr(BinStrToInt(PrevOctet)) 
else Result:=Result+' '; 

PrevOctet:=''; 
end; 

if Odd(Counter) then { only take two nibbles at a time } 
begin 
OctetStr:=Copy(PDU,Counter,2); 
OctetBin:=HexToBin(OctetStr); 

Charbin:=''; 
for Counter2:=1 to length(PrevOctet) do 
Charbin:=Charbin+PrevOctet[Counter2]; 

for Counter2:=1 to 7-length(PrevOctet) do 

Charbin:=OctetBin[8-Counter2+1]+Charbin; 

if BinStrToInt(Charbin)<>0 then Result:=Result+Chr(BinStrToInt(CharBin)) 
else Result:=Result+' '; 

PrevOctet:=Copy(OctetBin,1,length(PrevOctet)+1); 
end; 
end; 
end; 

function ReverseStr(SourceStr : string) : string; 
var Counter : integer; 
begin 
Result:=''; 

for Counter:=1 to length(SourceStr) do 
Result:=SourceStr[Counter]+Result; 
end;