Copying every nth element from one array to another

Question

Does anyone know of a way to copy every nth element from one array to another? For example, I have an array Data[x] and want to copy every third (3rd) element - Data[0], Data[3], Data[6] etc into a new array Data2[j]. I tried using a for loop but with no success.

void StoreData()
{
bufferPointer1 = &BufferA[0];
x=0;
i=0;
j=0;

while (x<NO_SAMPLES-1)
{
    Data[x] = *bufferPointer1;
    bufferPointer1++;
    x++;
    for (j=0; j<127; i++)
        {
        Data2[j] = Data[i+=3];
        j++;
        }
}
}

I am using a dspic33fj with xc16 – JBH Aug 16 '15 at 18:04 — JBH, Aug 16 '15 at 18:04

score 0 · Answer 1 · answered Aug 21 '15 at 18:19

Why aren't you declaring the variables in the function? All four of them seem to be used locally and should not be visible outside the function.

Why increment i in this section instead of j, Is this a typo?

   for (j=0; j<127; i++)
        {
        Data2[j] = Data[i+=3];
        j++;
        }

I would write it like this:

   for (j=0; j<127; j++)
        {
        Data2[j] = Data[i];
        i+=3;
        }
    i=0;                      // Reset pointer

Copying every nth element from one array to another

1 Answers1