/* Program 2-4: Toggling Three pins  
 * This program turns on the three pins with all the
 * possible combinations.  */

const int PINS[] = {5, 9, 10}; /* 3 pins */

void setup()
{
    /* configure output pins */
    for (int i = 0; i < 3; i++)
    {
        pinMode(PINS[i], OUTPUT);
    }
}

void loop()
{
    for (int i = 0; i < 8; i++)
    {
        digitalGroupWrite(PINS, 3, i);
        delay(500);
    }  
}

/* write to a group of output pins */
void digitalGroupWrite(const int* group, int length, int data)
{
    for (int i = 0; i < length; i++)
        digitalWrite(group[i], data & (1 << i) ? HIGH : LOW);
}