int datapin = 2; 
int clockpin = 3;
int latchpin = 4;

byte data = 0;

void setup()
{
  pinMode(datapin, OUTPUT);
  pinMode(clockpin, OUTPUT);  
  pinMode(latchpin, OUTPUT);
}


void loop()
{
  //oneAfterAnother();      // All on, all off
  //oneOnAtATime();       // Scroll down the line
  //pingPong();           // Like above, but back and forth
  //randomLED();          // Blink random LEDs
  //marquee();
  binaryCount();        // Bit patterns from 0 to 255
}


void shiftWrite(int desiredPin, boolean desiredState){
  bitWrite(data,desiredPin,desiredState); //Change desired bit to 0 or 1 in "data"
  shiftOut(datapin, clockpin, MSBFIRST, data); //Send "data" to the shift register
  digitalWrite(latchpin, HIGH); 
  digitalWrite(latchpin, LOW); 
}

void oneAfterAnother()
{
  int index;
  int delayTime = 100; // Time (milliseconds) to pause between LEDs
  for(index = 0; index <= 7; index++)
  {
    shiftWrite(index, HIGH);
    delay(delayTime);                
  }

  for(index = 7; index >= 0; index--)
  {
    shiftWrite(index, LOW);
    delay(delayTime);
  }
}

void oneOnAtATime()
{
  int index;
  int delayTime = 100; // Time (milliseconds) to pause between LEDs
  for(index = 0; index <= 7; index++)
  {
    shiftWrite(index, HIGH);    // turn LED on
    delay(delayTime);       // pause to slow down the sequence
    shiftWrite(index, LOW); // turn LED off
  }
}

void pingPong()
{
  int index;
  int delayTime = 100; // time (milliseconds) to pause between LEDs
  for(index = 0; index <= 7; index++)
  {
    shiftWrite(index, HIGH);    // turn LED on
    delay(delayTime);       // pause to slow down the sequence
    shiftWrite(index, LOW); // turn LED off
  }
  for(index = 7; index >= 0; index--)
  {
    shiftWrite(index, HIGH);    // turn LED on
    delay(delayTime);       // pause to slow down the sequence
    shiftWrite(index, LOW); // turn LED off
  }
}

void randomLED()
{
  int index;
  int delayTime = 100; // time (milliseconds) to pause between LEDs
  index = random(8);    // pick a random number between 0 and 7
  shiftWrite(index, HIGH);  // turn LED on
  delay(delayTime);     // pause to slow down the sequence
  shiftWrite(index, LOW);   // turn LED off
}

void marquee()
{
  int index;
  int delayTime = 200; // Time (milliseconds) to pause between LEDs
  for(index = 0; index <= 3; index++)
  {
    shiftWrite(index, HIGH);    // Turn a LED on
    shiftWrite(index+4, HIGH);  // Skip four, and turn that LED on
    delay(delayTime);       // Pause to slow down the sequence
    shiftWrite(index, LOW); // Turn both LEDs off
    shiftWrite(index+4, LOW);
  }
}

void binaryCount()
{
  int delayTime = 1000; // time (milliseconds) to pause between LEDs
  shiftOut(datapin, clockpin, MSBFIRST, data);
  digitalWrite(latchpin, HIGH);
  digitalWrite(latchpin, LOW);
  data++;
  delay(delayTime);
}