title: C++ add up all bytes in a structure
body: <p>Given a packed struct like this:</p>
  
  <pre><code>struct RSDPDescriptor {
      char Signature[8];
      uint8_t Checksum;
      char OEMID[6];
      uint8_t Revision;
      uint32_t RsdtAddress;
  } __attribute__ ((packed));
  </code></pre>
  
  <p>How can I sum all of the individual bytes in it?</p>