Parsing Hex Strings

Comments

• PhreaK Posts: 966

  April 2010

  The commas that you use when you form a string from hex values aren't actually part of the string, they are simply part of NetLinx's code syntax. To help explain this you have to remember that a string is an array of variables of type character. When you have something like

  temp = "$48,$65,$6c,$6c,$6f,$20,$57,$6f,$72,$6c,$64,$21"
  

  this is exactly the same as

  temp = "'Hello World!'"
  

  which is also the same as

  temp[1] = $48
  temp[2] = $65
  temp[3] = $6c
  temp[4] = $6c
  temp[5] = $6f
  temp[6] = $20
  temp[7] = $57
  temp[8] = $6f
  temp[9] = $72
  temp[10] = $6c
  temp[11] = $64
  temp[12] = $21
  set_length_string(temp, 12)
  

  
  So in your situation, if you are simply wanting a string exploded into an array of individual character you don't actually have to do anything, you can simply use:

  sTesting[characterNum]
  

  
  Hope this helps.

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• vining Posts: 4,368

  April 2010

  Here's some other examples that may help:

  //        1   2   3   4   5   6   7   8   9  10  11  12
  TEMP = "$48,$65,$6c,$6c,$6f,$20,$57,$6f,$72,$6c,$64,$21"
  fnDoHandleTemp(TEMP) ;
    
  DEFINE_FUNCTION fnDoHandleTemp(CHAR iTEMP[])
  
       {
       STACK_VAR CHAR RX_DATA_COPY[24] ;
       STACK_VAR CHAR RX_DATA_REMOVE[24] ;
       STACK_VAR CHAR RX_DATA_4BYTES[24] ;
       STACK_VAR INTEGER nLen ;
       STACK_VAR INTEGER i ;
  
       nLen = LENGTH_STRING(iTEMP) ;
       
       //THIS
       RX_DATA_4BYTES = GET_BUFFER_STRING(iTEMP,4) ;
       
       //OR
       RX_DATA_4BYTES = LEFT_STRING(iTEMP,4) ;
       
       //OR
       for(i = 1 ; i<= nLen ; i++)//COPY
  	  {
  	  RX_DATA_COPY[i] = iTEMP[i] ;//COPIES THE STRING
  	  }
  	  
       //OR
       for(i = 1 ; i<= nLen ; i++)//PAC MAN
  	  {
  	  RX_DATA_REMOVE[i] = GET_BUFFER_CHAR(iTEMP) ;//EATS THE STRING
  	  }
      
       //OR 
       SELECT
  	  {
  	  ACTIVE(iTEMP[1] == $48):
  	       {
  	       //do something
  	       }
  	  ACTIVE(iTEMP[8] == $6f):
  	       {
  	       //do something
  	       }
  	  ACTIVE(iTEMP[2] == $65 && iTEMP[12] == $21):
  	       {
  	       //do something
  	       }
  	  }
       }
  

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• vegastech Posts: 369

  April 2010

  Thanks. The posts are helping. I guess what's really getting me is that I need to take bytes 5,6,7,and 8 out of a total of 9 bytes, and reconfigure them so that byte 5 becomes byte 8, 6 becomes 7, 7 becomes 6, and 8 becomes 5, kind of like this:

  local_var char sDump[10]  //trash to remove 1st portion of reply
  local_var char sTime[4][2]  //container to store each hex value
  local_var integer nTime  //container to place all values together after converted from hex, using hextoi
  sDump = REMOVE_STRING(sProjInput,"$32,$2A,$0C,$00",1)
  sTime[1] = sProjInput[4]
  sTime[2] = sProjInput[3]
  sTime[3] = sProjInput[2]
  sTime[4] = sProjInput[1]
  nTime = hextoi(sTime)
  

  The array items in sTime never get populated with the method I tried above, when I go into debug mode. That was going to be my starting point in rearranging the array items (and then later use a for loop to shrink the code)

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• Prodigal Posts: 90

  April 2010

  Also keep in mind that each Hex value is 8 bits
  
  Much like a char. (char = 8bit, integer = 16bit ...)
  
  
  
  So, let's say you have the following Hex String:
  string: "$4E, $32, $8A, $0D"
  
  You don't need a multidimensional array to store these values.
  
  char copy_string[4]
  
  copy_string[1] = string[1]
  copy_string[2] = string[2]
  copy_string[3] = string[3]
  copy_string[4] = string[4]
  
  
  You don't need to make a
  char copy_string[4][2]
  
  string to acommodate those Hex values

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