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working with byte arrays

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  • J jkirkerx

    Didn't work at first, then I hardcoded the message length just for testing, and everything worked, including passing the string to the function. I need to figure out the length calculation. Working on that now, almost there, wow

    int msgLength = 80;
    char* szWords = new char[msgLength + 1];
    strncpy(szWords, recvbuf + 3, msgLength);

    This is the szWords,

    szWords 0x003e8f10 "ServerName;DELLC521-01;InstanceName;SQLEXPRESS;IsClustered;No;Version;10.50.1600Íýýýý««««««««þîþ"

    L Offline
    L Offline
    Lost User
    wrote on last edited by
    #19

    jkirkerx wrote:

    I need to figure out the length calculation.

    I gave you the code for that in my previous message; and I missed a line of code, so it should read:

    int msgLength = buffer[2] << 8 + buffer[1];
    char* szWords = new char[msgLength + 1];
    strncpy(szWords, buffer + 3, msgLength);
    szWords[msgLength] = '\0';

    Unrequited desire is character building. OriginalGriff I'm sitting here giving you a standing ovation - Len Goodman

    J 1 Reply Last reply
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    • L Lost User

      jkirkerx wrote:

      I need to figure out the length calculation.

      I gave you the code for that in my previous message; and I missed a line of code, so it should read:

      int msgLength = buffer[2] << 8 + buffer[1];
      char* szWords = new char[msgLength + 1];
      strncpy(szWords, buffer + 3, msgLength);
      szWords[msgLength] = '\0';

      Unrequited desire is character building. OriginalGriff I'm sitting here giving you a standing ovation - Len Goodman

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      J Offline
      jkirkerx
      wrote on last edited by
      #20

      So I still need to terminate the string with \0 Having trouble with the length, I did quick cheat with

      int msgLength = bytesReceived - 3;
      //int msgLength = recvbuf[2] << 8 + recvbuf[1];
      char* szWords = new char[msgLength + 1];
      strncpy(szWords, recvbuf + 3, msgLength);

      int msgLength with is an integer, I keep getting 0, is it because recvbuf[2] is returning the string, but wait, it's a byte representing a number. hmm

      L 1 Reply Last reply
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      • J jkirkerx

        So I still need to terminate the string with \0 Having trouble with the length, I did quick cheat with

        int msgLength = bytesReceived - 3;
        //int msgLength = recvbuf[2] << 8 + recvbuf[1];
        char* szWords = new char[msgLength + 1];
        strncpy(szWords, recvbuf + 3, msgLength);

        int msgLength with is an integer, I keep getting 0, is it because recvbuf[2] is returning the string, but wait, it's a byte representing a number. hmm

        L Offline
        L Offline
        Lost User
        wrote on last edited by
        #21

        Sorry, I really need to test my code before posting here, and check my operator precedence rules. In my defence, it is getting late and I'm half way through a nice bottle of Merlot :-D Try:

        int msgLength = (recvbuf[2] << 8) + recvbuf[1];

        Unrequited desire is character building. OriginalGriff I'm sitting here giving you a standing ovation - Len Goodman

        J 1 Reply Last reply
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        • L Lost User

          Sorry, I really need to test my code before posting here, and check my operator precedence rules. In my defence, it is getting late and I'm half way through a nice bottle of Merlot :-D Try:

          int msgLength = (recvbuf[2] << 8) + recvbuf[1];

          Unrequited desire is character building. OriginalGriff I'm sitting here giving you a standing ovation - Len Goodman

          J Offline
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          jkirkerx
          wrote on last edited by
          #22

          Hey no problem, I thought perhaps I had to solve it as a test of some sort. I answer asp.net server control questions on my last beer before I turn off the computer at night. I want to thank you for helping me. It was really bring me down, and everyone just sort of gave me a blank look, "Its so easy, come on, that c++ 101". Words cannot express the gratitude for the help. I really appreciate it, and yes, code project pulls through with expert help.

          G L 2 Replies Last reply
          0
          • J jkirkerx

            Hey no problem, I thought perhaps I had to solve it as a test of some sort. I answer asp.net server control questions on my last beer before I turn off the computer at night. I want to thank you for helping me. It was really bring me down, and everyone just sort of gave me a blank look, "Its so easy, come on, that c++ 101". Words cannot express the gratitude for the help. I really appreciate it, and yes, code project pulls through with expert help.

            G Offline
            G Offline
            Goto_Label_
            wrote on last edited by
            #23

            :laugh: great fun but we didnt solve the passing of byte arrays

            J 1 Reply Last reply
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            • G Goto_Label_

              :laugh: great fun but we didnt solve the passing of byte arrays

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              jkirkerx
              wrote on last edited by
              #24

              oh no, it got solved! Richard wrote some code to extract the message size from byte 2, copy just the message to a new char array, termintate it with \0, and pass it to my function for processing I'm stoked, surfer happiness, yeah! I've been banging my head for days on this, feeling pretty stupid about it. Thanks for watching the show! msgLength = (recvbuf[2] << 8) + recvbuf[1]; szWords = new char[msgLength + 1]; strncpy(szWords, recvbuf + 3, msgLength); szWords[msgLength] = '\0'; _process_SQL_BufferData(szWords, bytesReceived);

              1 Reply Last reply
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              • J jkirkerx

                Hey no problem, I thought perhaps I had to solve it as a test of some sort. I answer asp.net server control questions on my last beer before I turn off the computer at night. I want to thank you for helping me. It was really bring me down, and everyone just sort of gave me a blank look, "Its so easy, come on, that c++ 101". Words cannot express the gratitude for the help. I really appreciate it, and yes, code project pulls through with expert help.

                L Offline
                L Offline
                Lost User
                wrote on last edited by
                #25

                Happy to help, it's what makes CodeProject fun! That and your appreciation.

                Unrequited desire is character building. OriginalGriff I'm sitting here giving you a standing ovation - Len Goodman

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                • J jkirkerx

                  I understand now that the data I receive from a socket is a byte array. But I don't understand how to pass the byte array to a function for further processing. Plus I'm not sure if I should leave it as a byte array, or try to convert it to a string, so I can extract data from it. I'm confused as to whether this buffer is a pointer to data somewhere else, and If I need to make a copy of it, before passing it to a function. When I pass it to a function, the data is lost. Kind of tired of going around in circles here on this, and I need road map to head in the right direction. I make my receive buffer char recvbuf[256]; I get data 0x05 '' 0x54 'T' 0x53 'S' 0x65 'e' And I try to pass it to a function for processing. Unless just extracting the info I need does not require a function. Suggestion? void _process(char *pbuffer) { }

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                  jschell
                  wrote on last edited by
                  #26

                  jkirkerx wrote:

                  When I pass it to a function, the data is lost.

                  What does that mean exactly? One possibility is that you are misusing the buffer. If so that has nothing to do with sockets nor with how you chose to process the data.

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                  • J jschell

                    jkirkerx wrote:

                    When I pass it to a function, the data is lost.

                    What does that mean exactly? One possibility is that you are misusing the buffer. If so that has nothing to do with sockets nor with how you chose to process the data.

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                    jkirkerx
                    wrote on last edited by
                    #27

                    Only the first char in the byte array passed to the function. I suspect that the 2nd byte was the data size of the packet, and the 3 byte was used for some control purpose, or an extension of the 2nd byte or something. So when I go the function I passed the data to, just the first byte is there 'T' or something. I think it was a 0x05. I have it working now, so far so good, and it's not crashing yet. I ended up passing the data in a vector to the function.

                    J 1 Reply Last reply
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                    • J jkirkerx

                      Only the first char in the byte array passed to the function. I suspect that the 2nd byte was the data size of the packet, and the 3 byte was used for some control purpose, or an extension of the 2nd byte or something. So when I go the function I passed the data to, just the first byte is there 'T' or something. I think it was a 0x05. I have it working now, so far so good, and it's not crashing yet. I ended up passing the data in a vector to the function.

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                      jschell
                      wrote on last edited by
                      #28

                      Doesn't matter what the other data was. What matters is that it was missing. Some possible reasons - You copied from one buffer to another incorrectly. - You overwrote the original buffer - You didn't have all the data in the buffer in the first place. - You are indexing incorrectly in the processing stream.

                      J 1 Reply Last reply
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                      • J jschell

                        Doesn't matter what the other data was. What matters is that it was missing. Some possible reasons - You copied from one buffer to another incorrectly. - You overwrote the original buffer - You didn't have all the data in the buffer in the first place. - You are indexing incorrectly in the processing stream.

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                        jkirkerx
                        wrote on last edited by
                        #29

                        I think it's just i no clear concept of c++, and I should buy one of those thick books on it.

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