int tDelay = 200;
int latchPin = 11;      // (11) ST_CP [RCK] on 74HC595
int clockPin = 9;      // (9) SH_CP [SCK] on 74HC595
int dataPin = 12;     // (12) DS [S1] on 74HC595

byte leds = 0;

void setup() {
  // put your setup code here, to run once:
  pinMode (latchPin, OUTPUT); 
  pinMode (dataPin, OUTPUT); 
  pinMode (clockPin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  leds = 0;
  updateShiftRegister();
  delay(tDelay);
  for (int i = 0; i < 8; i++)
  {
    bitSet(leds, i);
    updateShiftRegister();
    delay(tDelay);
  }
}

void updateShiftRegister()
{
  digitalWrite (latchPin, LOW);
  shiftOut (dataPin, clockPin, LSBFIRST, leds); 
  digitalWrite (latchPin,HIGH);
}