Handling AnsiString and its Hex code in Unicode aware Delphi versions

Question

I am running a legacy application, built on Delphi2007, where we used to handle non-English characters by storing 2byte Hex code of the character in the DB. While reading we apply char() to convert these Hex code to String.

String to Hex (before saving to DB):

strHex := Format( '%x', [ Byte( strText[ lIndex ] ) shr 4 ] );
DataStr[ lPos ] := strHex[ 1 ];
inc( lPos );

strHex := Format( '%x', [ Byte( strText[ lIndex ] ) and $0F ] );
DataStr[ lPos ] := strHex[ 1 ];
inc( lPos );

//in simple I am saving the Hex code to pcData

Hex to String (after reading from DB):

strText := strText + Chr( StrToInt('$'+ DataStr[lPos] + DataStr[lPos + 1]))

This code started breaking after moving to Delphi XE7, where string is treated as UniCode String, we explicitly have to convert the string to AnsiString type.

Converting below string to hex
ТуцЕфылАшдеук8311
In Delphi 2007 gives:
\D2\F3\F6\C5\F4\FB\EB\C0\F8\E4\E5\F3\EA8311
In Delphi XE7 gives:
\22\43\46\1A\33\4B\4B\48\44\42\14\44\49\33\351522

I would like to know the best way I can modify this code such that I can handle my legacy data.

Answer 1

According to comments, you just need to decode this data to a native Unicode string. Do that like so:

1. Read the encoded text from the database into a string variable.
2. Decode that text into a byte array rather than a string. Your Delphi 2007 code can be used pretty much as it, but it needs to write to a byte array rather than a string.
3. That byte array is ANSI 1251 encoded. Decode it with TEncoding.GetString. You'll need to create an instance of the TEncoding class with the correct code page, Encoding := TEncoding.GetEncoding(1251).