SA> struct MESSAGErecord 
 SA> {
 SA> // other stuff
 SA> unsigned char  Attribute;
 SA>               /* Bit 0 : Enable EchoInfo
 SA>                1 : Combined access
 SA>                2 : File attaches
 SA>                3 : Allow aliases
 SA>                4 : Use SoftCRs as characters
 SA>                5 : Force handle
 SA>                6 : Allow deletes
 SA>                7 : Is a JAM area */
 SA> // more stuff
 SA> };

 SA> Simple question. How do I modify the values?

Let's simplify things...

struct foo
{
  unsigned char bar;
};

#define BAR_ENABLEECHOINFO 0x01                    /* bit 0 'on' */
#define BAR_COMBINEDACCESS 0x02                    /* bit 1 'on' */
#define BAR_FILEATTACHES   0x04 /* !!! - not 3! */ /* bit 2 'on' */
#define BAR_ALLOWALIASES   0x08                    /* bit 3 'on' */
/* etc - 0x10, 0x20, 0x40, 0x80 */

struct foo f;

f.bar |= BAR_ENABLEECHOINFO; /* turn on bit 0 */
f.bar &= ~BAR_COMBINEDACCESS; /* turn off bit 1 */
if (f.bar & BAR_FILEATTACHES) /* if bit 2 is on... */
  do_something();
f.bar ^= BAR_ALLOWALIASES; /* toggle bit 3 */

This is all no different from non-struct bit access.

Hope this helps.


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