int dataPin = 4;
int latchPin = 6;
int clockPin = 7;

void setup() {
  pinMode(dataPin, OUTPUT);
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  Serial.begin(9600);
}

void loop() {
for (int numberToDisplay = 0; numberToDisplay < 256; numberToDisplay++) {
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, numberToDisplay);
  digitalWrite(latchPin, HIGH);
  delay(500);
  } 
}