int BASE = 2 ; // the I/O pin for the first LED
int NUM = 6; // number of LEDs
void setup()
{
for (int i = BASE; i < BASE + NUM; i ++)
{
pinMode(i, OUTPUT); // set I/O pins as output
}
}
void loop()
{
for (int i = BASE; i < BASE + NUM; i ++)
{
digitalWrite(i, LOW); // set I/O pins as “low”, turn off LEDs one by one.
delay(200); // delay
}
for (int i = BASE; i < BASE + NUM; i ++)
{
digitalWrite(i, HIGH); // set I/O pins as “high”, turn on LEDs one by one
delay(200); // delay
}
}