enum data type

typedef enum X
   {
   base     = 90,
   primus   = 91,
   secundus = 92,
   tertius  = 93
   } X;

makes it really easy to find the value for a symbolic name, or conversely search for the value when you find it in a hex dump.

even easier find in a hex dump

typedef enum X
   {
   base     = 0x5a,
   primus   = 0x5b,
   secundus = 0x5c,
   tertius  = 0x5d
   } X;

now to make it even 'safe' (it is better to confuse the debuuging individual a bit than open the possibility for overlaps)

typedef enum X
   {
   base     = 90,          // 0x5a
   primus   = base - 1,    // 0x59
   secundus = primus - 1,  // 0x58
   tertius  = tertius - 1  // 0x57
   } X;

for debugging (search) purposes I always define constants in hex (or in decimal with a comment of the hex value). Yes, I, once in a blue moon, find things like
if (value == symbolic_name) // 0x47
where the value is wrong because of an update, but once you have learned to take such comments with a grain of salt, they are helpful. There is, of course, a 'rule' that when such is found the value in the comment must be corrected in the source.

Erik

typedef enum X
   {
   base     = 90,
   primus   = 91,
   secundus = 92,
   tertius  = 93
   } X;

makes it really easy to find the value for a symbolic name, or conversely search for the value when you find it in a hex dump.

even easier find in a hex dump

typedef enum X
   {
   base     = 0x5a,
   primus   = 0x5b,
   secundus = 0x5c,
   tertius  = 0x5d
   } X;

now to make it even 'safe' (it is better to confuse the debuuging individual a bit than open the possibility for overlaps)

typedef enum X
   {
   base     = 90,          // 0x5a
   primus   = base - 1,    // 0x59
   secundus = primus - 1,  // 0x58
   tertius  = tertius - 1  // 0x57
   } X;

for debugging (search) purposes I always define constants in hex (or in decimal with a comment of the hex value). Yes, I, once in a blue moon, find things like
if (value == symbolic_name) // 0x47
where the value is wrong because of an update, but once you have learned to take such comments with a grain of salt, they are helpful. There is, of course, a 'rule' that when such is found the value in the comment must be corrected in the source.

Erik

typedef enum X
   {
   base     = 90,          // 0x5a
   primus   = base - 1,    // 0x59
   secundus = primus - 1,  // 0x58
   tertius  = tertius - 1  // 0x57
   } X;

If you're going to write out the values anyway in the comments, you might as well just assign them directly rather than have to do both that and mess about with the decrementing scheme.

This scheme has the double disadvantage that the comments can get out-of-step with the real values, and you can get the decrementing scheme wrong as well!

I would either go for explicit numbers in the enumerator, or rearrange the symbols to make use of the normal increment.

But on the other hand, I normally don't spend too much time debugging, where I need to look at the raw numbers in the debugger.

If doing embedded, I often try to get a prototype built with extra memory, so I can have a bit of helper info available.

A trick I do use when playing with enumerators is to:

/* operators.h */
T(ADD)
T(SUB)
T(MUL)
T(DIV)

#define T(x) x,

enum OP {
    #include "operators.h"

};

#undef T

#define T(x) #x,

char* op_names[] = {
    #include "operators.h"

};

op = ADD;

printf("operator %s\n",op_names[op]);

and i've got a question about i2c function.
1) is it true that i can set any fixed baud rate (clock) from 0 to 100KHz?
2) if i set the bit I2CFREQ, what value should i put into the register if i'm using crystal 4MHz?
4) if i set the bit I2CFREQ2,SMP=0, is the baud rate fixed to 400KHz or i'm free to set any baud rate from 0 to 400KHZ? what value should i put into I2CADD then using a 20MHZ crystal?

answers are appreciated.
Thank you.

Why do you think this is an appropriate question in a thread about the "enum data type"?

Does it have anything whatsoever to do with the preceding discussions?!

Not only off-topic, but also incomplete. No mention of used processor.