array adding int.

It's hard to figure things out since you didn't specify any variable types.

i++;

How is the variable i declared. I think you probably want it to be static and unsigned char. If it's not static you can be certain that it will not retain its value between invocations.

if(i == 10){i == 0;}

I think you mean i = 0 instead of i == 0. Also, what happens if i = 11?

Why not use if (i>=10) i=0;? This avoids problems if i is outside the range of valid array indexes. This comparison assumes that i is an unsigned type (which never goes negative).

array[i] = data;

data = 0;

for (a = 0; a < 10 ; a++)
	{data = data + array[i];}

I understand what you're doing here, but adding up all of the array contents each time takes a long time (imagine if your array was 100 elements long). Also, since you accumulate the array contents into data, data's type should probably be larger than the array (the array unsigned char and data unsigned int) to avoid overflow problems.

Instead of accumulating the entire array each time, you could just subtract array[i] (since it's the oldest value in the array), put the new data into array [i], and add the new data to your total.

I would probably do something like this:

unsigned int func (unsigned char data)
{
#define ARRAY_SIZE 10

static unsigned char ndx = 0;
static unsigned char array [ARRAY_SIZE] = { 0, };
static unsigned int array_ttl;

if (++i >= ARRAY_SIZE) i = 0;

array_ttl -= array[ndx]; // remove oldest data
array_ttl += data;       // add newest data
array[ndx] = data;       // add newest data to array

return (array_ttl);      // return total
or
return (array_ttl/ARRAY_SIZE);  // return average
}

This routine always takes the same amount of time to execute no matter how big the array is. It also has the advantage of being able to change the array size in a single place (the #define).

Jon

It's hard to figure things out since you didn't specify any variable types.

i++;

How is the variable i declared. I think you probably want it to be static and unsigned char. If it's not static you can be certain that it will not retain its value between invocations.

if(i == 10){i == 0;}

I think you mean i = 0 instead of i == 0. Also, what happens if i = 11?

Why not use if (i>=10) i=0;? This avoids problems if i is outside the range of valid array indexes. This comparison assumes that i is an unsigned type (which never goes negative).

array[i] = data;

data = 0;

for (a = 0; a < 10 ; a++)
	{data = data + array[i];}

I understand what you're doing here, but adding up all of the array contents each time takes a long time (imagine if your array was 100 elements long). Also, since you accumulate the array contents into data, data's type should probably be larger than the array (the array unsigned char and data unsigned int) to avoid overflow problems.

Instead of accumulating the entire array each time, you could just subtract array[i] (since it's the oldest value in the array), put the new data into array [i], and add the new data to your total.

I would probably do something like this:

unsigned int func (unsigned char data)
{
#define ARRAY_SIZE 10

static unsigned char ndx = 0;
static unsigned char array [ARRAY_SIZE] = { 0, };
static unsigned int array_ttl;

if (++i >= ARRAY_SIZE) i = 0;

array_ttl -= array[ndx]; // remove oldest data
array_ttl += data;       // add newest data
array[ndx] = data;       // add newest data to array

return (array_ttl);      // return total
or
return (array_ttl/ARRAY_SIZE);  // return average
}

This routine always takes the same amount of time to execute no matter how big the array is. It also has the advantage of being able to change the array size in a single place (the #define).

Jon

for (a = 0; a < 10 ; a++)
	{data = data + array[i];}

"I understand what you're doing here, but adding up all of the array contents..."

That might be what he's trying to do, but it's not what that piece of code does, is it?

The loop uses 'a' to repeat the statement

data = data + array[i];

ten times.
'i' does not change during the loop!
Therefore, each time around the loop, it adds the same element from the array!

Why would you use

unsigned char array [ARRAY_SIZE]

to store integers in the array?