sorry that should have been just data[].
hmm, so maybe my for loop should look like this:
for (int i = 0; i < sizeof(data_array) - 1; i++)
data_array[i] = data_array[i + 1];
edit: ok it runs now, but for some reason my array seems to be only of size 2, but when I print out sizeof(data) it is 40? And I thought I set it to 10...