Re: Newbie question: How to define a class that will work on bits from a binary file?

"Victor Bazarov" <>
Wed, 14 May 2008 22:13:40 -0400
Damfino wrote:

Hi all,
Newbie question here wrt defining a class that will work on bits read
from a binary file. How would you go about doing it? As an example
please look at the structure of my data given below. The data comes in
40 byte packets via stdin or a binary file.
 syncByte (8bits)
 XML_type (2bits)
 XML_subtype (2bits)
 record_value (3bits)
 playout_flag (1bit)
 if (playout_flag=='1') {
    playout_length (8bits)
    for (i=0; i< playout_length; i++){
 payload to fill the rest of the 40 bytes
How would this be defined as a class?

// assuming that 'char' is 8 bits

class DataPacket {
    // somehow control the alignment and make it 1 byte
    // to avoid padding between members of this class
    char syncByte; // not sure you need this to be kept
    struct BitStuff {
        unsigned XML_type:2;
        unsigned XML_subtype:2;
        unsigned record_value:3;
        unsigned payout:1;
    } fields;
    char restOfPacket[38];
    // member functions go here

How would you retrieve the values for the different variables within
the packet?

Not sure what retrieval you're talking about.

How would you set the variables to a specific value?

By initialising or assigning them.

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