Logic Suggestion

[logic4fun]

Hi guys,
I am again in the world of confusion. I am working with a state engine where it retrieves data states of different persons from a database for a particular interval of time and i will modify them in my "C" program. The question is everytime i need the last state of that particular person when i am dealing the next Interval.

Note: The persons are Random i.e. there is no possibility that they come in a particular order in an interval

the possible solutions i thought are.
* Store the personName and State in the two dimensional array and search for it when ever i change the interval.(Dont KNOW HOW TO IMPLEMENT :-(

* Another idea is to load the last states into a Temporary table of DB2 database and query them..Which will kill lot of time because of the querying..I CAN DO THIS BUT POOR IMPLEMENTATION...

ANY SUGGESTIONS...

Thanks in advance
logic4fun

 

[Salem]

> Which will kill lot of time because of the querying
Whilst this may be true, is it likely to be non-starter without trying it?

What sort of table sizes are you talking about, and how many transactions (or transactions per second) are you likely to be performing?

The C solution may be more optimal, but the cost of implementation is also greater. Rule 1 of this page may apply

http://www.leto.net/docs/C-optimization.html#Gotchas

> Store the personName and State in the two dimensional array
To keep the name associated with the state, I would use a structure.

 

[dlkfjdlkfjdlfkd]

Easy:

You could store each person retrieved in an array and then do a linear search or binary search on the array to retrieve it (for the latter, you would have to keep the array sorted).

Your framework could be something like this:

#define MAXNAME 50
#define MAXPERSONS 100

struct person {
char name[MAXNAME + 1];
char state[3];
} persons[MAXPERSONS];
int person_count;

to insert:

int person_insert(const char *name, const char *state)
{
struct person p;
strcpy(p.name, name);
strcpy(p.state, state);
if (person_count == MAXPERSON) return -1;
persons[person_count++] = p;
return 0;
}
struct person *person_search(const char *name)
{
int i;
struct person *result = NULL;

for (i = 0; result == NULL && i < person_count; ++i)
if (strcmp(persons.name, name) == 0)
result = &persons;
return result;
}

This is about the slowest method, but may be adequate for your purposes.

Faster options would be using self-ordering data structures such as binary search trees or hash tables, which would take a while to explain here. K&R 2 has examples of both which you could pretty much copy and paste from the book.