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byte[] cast to a string

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  • J Jorgen Sigvardsson

    Take a look at cultures and globalization. I assume you need an 8 bit encoder/decoder using some codepage. -- I am of The Clan of Xymox. I wear a pink kilt!

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    Tym
    wrote on last edited by
    #5

    I'm not too familiar with the encoders/decoders or how unicode particularly works, but my concern here is that if i have for example: byte b1=0x85; byte b2=0x7f; the data i want to actually send should be: 0x857f which I believe would be a valid unicode char. first of all, i don't want and encoder to "pad" my bytes when building a string (0x0085007f), nor do I want a decoder interpretting the bytes and apparent chars... thereby messing up the raw bits. I tried forgetting about building the array as a string and just defining it as a byte[] in the struct, but I couldn't get the marshalling right (unable to marshal struct as unmanaged type; cannot determine size...) When using a string, I am not getting a runtime error, I am just not building the string properly because I am getting incorrect results. I am open for any and all suggestions! Thanks

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    • T Tym

      I'm not too familiar with the encoders/decoders or how unicode particularly works, but my concern here is that if i have for example: byte b1=0x85; byte b2=0x7f; the data i want to actually send should be: 0x857f which I believe would be a valid unicode char. first of all, i don't want and encoder to "pad" my bytes when building a string (0x0085007f), nor do I want a decoder interpretting the bytes and apparent chars... thereby messing up the raw bits. I tried forgetting about building the array as a string and just defining it as a byte[] in the struct, but I couldn't get the marshalling right (unable to marshal struct as unmanaged type; cannot determine size...) When using a string, I am not getting a runtime error, I am just not building the string properly because I am getting incorrect results. I am open for any and all suggestions! Thanks

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      Jorgen Sigvardsson
      wrote on last edited by
      #6

      Well.. what is the byte array made of? Do you know what character set it is made of? The ASCII character set is 7-bit only, therefore anything above 0x7f is "invalid" and not representable by using that character set. Please see Encoding.GetEncoding() it should solve your problem. :) -- I am of The Clan of Xymox. I wear a pink kilt!

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      • T Tym

        I am trying to take a byte array and cast it to a string. The closest I have come is: ASCIIEncoding.GetString Method (Byte[]) However, there is a restriction: "Any element of the bytes array that is greater than hexadecimal 0x7F is translated to a Unicode question mark ('?')." I need to keep that extra bit. Tym!

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        Blake Coverett
        wrote on last edited by
        #7

        While it is counter-intuitive, what you want in this case is UnicodeEncoding.GetString(byte[]). Because the data inside a string is natively stored using that UnicodeEncoding, it is a null transform, leaving your bytes alone. (I suspect you'd better have an even number of bytes in your array if you want this to work. Herein lies a subtle inconsistency between BSTR's and System.Strings. BSTR's kind of admit to being used to pass random data around, and hence support odd numbers of bytes even though they are supposedly a strings of 16bit values. Your API hopefully won't care if you pad an extra null on the end if the length was odd.) -Blake

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        • J Jorgen Sigvardsson

          Well.. what is the byte array made of? Do you know what character set it is made of? The ASCII character set is 7-bit only, therefore anything above 0x7f is "invalid" and not representable by using that character set. Please see Encoding.GetEncoding() it should solve your problem. :) -- I am of The Clan of Xymox. I wear a pink kilt!

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          Tym
          wrote on last edited by
          #8

          The byte array is made of bytes. They do not represent characters.

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          • T Tym

            The byte array is made of bytes. They do not represent characters.

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            Jorgen Sigvardsson
            wrote on last edited by
            #9

            Then... uhm. why, if I may ask, on earth are you trying to cast an array of bytes into a string? :confused: -- I am of The Clan of Xymox. I wear a pink kilt!

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            • B Blake Coverett

              While it is counter-intuitive, what you want in this case is UnicodeEncoding.GetString(byte[]). Because the data inside a string is natively stored using that UnicodeEncoding, it is a null transform, leaving your bytes alone. (I suspect you'd better have an even number of bytes in your array if you want this to work. Herein lies a subtle inconsistency between BSTR's and System.Strings. BSTR's kind of admit to being used to pass random data around, and hence support odd numbers of bytes even though they are supposedly a strings of 16bit values. Your API hopefully won't care if you pad an extra null on the end if the length was odd.) -Blake

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              Tym
              wrote on last edited by
              #10

              yeah, it's always going to be a multiple of 4 bytes, so I don't need to worry about padding. I used the UnicodeEncoding and get a different, yet still incorrect, result. I wonder if I am not declaring the struct correctly or I don't know, I feel that I am so close, but am just missing something... Thanks for your help.

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              • J Jorgen Sigvardsson

                Then... uhm. why, if I may ask, on earth are you trying to cast an array of bytes into a string? :confused: -- I am of The Clan of Xymox. I wear a pink kilt!

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                Tym
                wrote on last edited by
                #11

                Well, that is not necessarily my ultimate solution, but I have gotten runtime errors when trying to pass the data as arrays. I may be able to, but I can't quite get everything right. I chose a string at first because it is in a struct that mimics an unmanaged struct and the original, unmanaged struct defines it as a string. The whole struct is then passed by reference in an interop call to a windows API function. When I use a string, the code runs, but the data in the string is incorrect and I get incorrect results. When I have used byte[] or char[] or even StringBuilder, I got runtime errors, saying the struct cannot converted to unmanaged.... the size cannot be determined. I might be able to do it both ways, I just need to figure out what I'm missing...:((

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                • T Tym

                  Well, that is not necessarily my ultimate solution, but I have gotten runtime errors when trying to pass the data as arrays. I may be able to, but I can't quite get everything right. I chose a string at first because it is in a struct that mimics an unmanaged struct and the original, unmanaged struct defines it as a string. The whole struct is then passed by reference in an interop call to a windows API function. When I use a string, the code runs, but the data in the string is incorrect and I get incorrect results. When I have used byte[] or char[] or even StringBuilder, I got runtime errors, saying the struct cannot converted to unmanaged.... the size cannot be determined. I might be able to do it both ways, I just need to figure out what I'm missing...:((

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                  Jorgen Sigvardsson
                  wrote on last edited by
                  #12

                  Tym! wrote: Well, that is not necessarily my ultimate solution, but I have gotten runtime errors when trying to pass the data as arrays. I may be able to, but I can't quite get everything right. I'm still confident though that this is the right way to do it. God knows what the .NET runtime does to strings when you're not watching... :rolleyes: -- I am of The Clan of Xymox. I wear a pink kilt!

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                  • T Tym

                    yeah, it's always going to be a multiple of 4 bytes, so I don't need to worry about padding. I used the UnicodeEncoding and get a different, yet still incorrect, result. I wonder if I am not declaring the struct correctly or I don't know, I feel that I am so close, but am just missing something... Thanks for your help.

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                    Jeff Varszegi
                    wrote on last edited by
                    #13

                    What about something like this? I didn't test, so it might have a typo, but would this sort of approach work? I don't know how you want the ordering. -Jeff

                    private const string blankString = "";
                    public static string ConvertToString(byte[] bytes) {
                    if (bytes == null) {
                    return blankString;
                    }
                    int length = bytes.Length;
                    if (length == 0) {
                    return blankString;
                    }
                    else if ((length % 2) == 0) {
                    length /= 2;
                    char[] chars = new char[length];
                    for(int charIndex = 0, byteIndex = 0; charIndex < length; charIndex++, byteIndex += 2) {
                    chars[charIndex] = (char)((((int)bytes[byteIndex]) << 8) + ((int)bytes[byteIndex + 1]));
                    }
                    return new string(chars);
                    }
                    else {
                    length /= 2;
                    char[] chars = new char[length + 1];
                    for(int charIndex = 0, byteIndex = 0; charIndex < length; charIndex++, byteIndex += 2) {
                    chars[charIndex] = (char)((((int)bytes[byteIndex]) << 8) + ((int)bytes[byteIndex + 1]));
                    }
                    chars[length] = (char)(((int)bytes[bytes.Length - 1]) << 8);
                    return new string(chars);
                    }
                    }

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                    • T Tym

                      I am trying to take a byte array and cast it to a string. The closest I have come is: ASCIIEncoding.GetString Method (Byte[]) However, there is a restriction: "Any element of the bytes array that is greater than hexadecimal 0x7F is translated to a Unicode question mark ('?')." I need to keep that extra bit. Tym!

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                      leppie
                      wrote on last edited by
                      #14

                      Like Jorgen said u need to get your codepage. Get it with Encoding.Default. that should fix the issue. leppie::AllocCPArticle("Zee blog");
                      Seen on my Campus BBS: Linux is free...coz no-one wants to pay for it.

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                      • T Tym

                        I am trying to take a byte array and cast it to a string. The closest I have come is: ASCIIEncoding.GetString Method (Byte[]) However, there is a restriction: "Any element of the bytes array that is greater than hexadecimal 0x7F is translated to a Unicode question mark ('?')." I need to keep that extra bit. Tym!

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                        Tym
                        wrote on last edited by
                        #15

                        Thanks everyone for your help. Just to let you know, i ended up using encoding.default to get it working. Got a little lesson on .net text... Thanks again!

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