int latchPin = 5; 
int clockPin = 6; 
int dataPin = 4; 
byte leds = 0; 

void setup() 
{ 
 pinMode(latchPin, OUTPUT); 
 pinMode(dataPin, OUTPUT); 
 pinMode(clockPin, OUTPUT); 
} 

void loop() 
{ 
 leds = 0; 
 updateShiftRegister(); 
 delay(500); 
 for (int i = 0; i < 8; i++) 
 { 
 bitSet(leds, i); 
 updateShiftRegister(); 
 delay(500); 
 } 
} 

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