Array size

Projects Programming
7

SouthernAtHeart:
So this would be fine:

buttonPin[7] = {13,12,11,10,5,9,6};

Of course it should have a type, eg.

byte buttonPin[7] = {13,12,11,10,5,9,6};

And as maniacbug said, the compiler can figure out the size:

byte buttonPin[] = {13,12,11,10,5,9,6};

But if you need to know it, now you have to find it out, eg.

for (int i = 0; i < sizeof buttonPin; i++)
  pinMode (buttonPin [i], OUTPUT);

That only works if the array happens to be of "unit" sized things (like byte, char).

Otherwise as lloyddean said, you have to divide by the unit size:

for (int i = 0; i < (sizeof buttonPin) / (sizeof buttonPin [0]); i++)
  pinMode (buttonPin [i], OUTPUT);

I usually use a define to do that:

// number of items in an array
#define NUMITEMS(arg) ((unsigned int) (sizeof (arg) / sizeof (arg [0])))

So now you can do:

for (int i = 0; i < NUMITEMS (buttonPin); i++)
  pinMode (buttonPin [i], OUTPUT);