如何跟踪C中的struct成员值更改？

Question

struct STATE{
  uint8 bit;
  uint8 cop;
}
STATE *state_array[1024];

state_aray[0]->bit = 8;     
state_aray[0].cop =  8;
state_aray[1]->bit = 0;     
state_aray[1].cop = state_aray[1]->bit & 8 != state_aray[0]->bit & 8
state_aray[2]->bit = 12;   
state_aray[2].cop = state_aray[1]->bit & 8 != state_aray[0]->bit & 8 && state_aray[2]->bit & 8 != state_aray[1]->bit & 8
state_aray[3]->bit = 0;     
state_aray[3].cop = state_aray[1]->bit & 8 != state_aray[0]->bit & 8 && state_aray[2]->bit & 8 != state_aray[1]->bit & 8 && state_aray[3]->bit & 8 != state_aray[2]->bit & 8
state_aray[4]->bit = 8;     
state_aray[4].cop = ...

state_aray[5].cop = ... ...
...
state_aray[100].cop = ... ...... ......... ....... ......... ....... ...... ....... ............... ........ ...... ............ .... ......... ...... ..

is there a way to only use state_aray[i-1]->cop and state_aray[i-1]->bit and state_aray[i]->bit to get state_aray[i]->cop?

tks

Answer 1

Won't work. There's no "I'm a member of this structure" mechanism in C, as opposed to OOP's "this" or "self" concepts. That's why in C you simply hide your structure implementation and provide functions to change the values in which you sneakily set other values.

STATE *create_state(void)
{
    STATE *retval;

    if( (retval = malloc(sizeof(STATE))) == NULL )
        return NULL;
    retval->cop = -1;
    retval->bit = 0;
    return retval;
}

void set_state(STATE *st, int val)
{
    st->bit = val;
    st->cop++;
}

int has_state_changed(STATE *st)
{
    return st->cop;
}