Arduino C Program LED Blink

I wrote a little example Arduino C Program that lets the LEDs blink in 5 different ways. You could download the Software from Arduino – Software.

// the setup routine runs once when you press reset:
#define START_PIN 0
#define END_PIN 7

void setup() {                
  // initialize the digital pin as an output.
  for(int i = 0;i<=END_PIN;i++){
  pinMode(i, OUTPUT); 
  }  
}
int sleep = 40;
// the loop routine runs over and over again forever:
void loop() { 
  //mod 1
  for(int i = START_PIN;i<=END_PIN;i++){
  digitalWrite(i, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(sleep);               // wait for a second
  digitalWrite(i, LOW);    // turn the LED off by making the voltage LOW
  delay(sleep);               // wait for a second
  }
  for( int i = END_PIN;i>START_PIN;i--){
  digitalWrite(i, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(sleep);               // wait for a second
  digitalWrite(i, LOW);    // turn the LED off by making the voltage LOW
  delay(sleep);               // wait for a second
  }
  //mod 2
  for( int i = START_PIN;i<=END_PIN;i++){
    digitalWrite(i, HIGH);
  delay(sleep);  
  }
  for( int i = START_PIN;i<=END_PIN;i++){
  digitalWrite(i, LOW);
  }
  for( int i = END_PIN;i>START_PIN;i--){
  digitalWrite(i, HIGH); 
  delay(sleep); 
  }
  for( int i = START_PIN;i<=END_PIN;i++){
  digitalWrite(i, LOW);
  }
  //mod 3
  for(int x = 1;x<=START_PIN+END_PIN;x++){
    for( int i = START_PIN;i<=END_PIN;i++){
    digitalWrite(i, HIGH);
    }
    delay((sleep*10)/x);
    for( int i = START_PIN;i<=END_PIN;i++){
    digitalWrite(i, LOW);
    }
    delay((sleep*10)/x);
  }
  //mod 4
  for(int x = 0;x<=20;x++){
    for( int i = START_PIN;i<=END_PIN;i++){
      if(i%2){
        digitalWrite(i, HIGH);
      }else{
        digitalWrite(i, LOW);
      }
    }
    delay(sleep);
      for( int i = START_PIN;i<=END_PIN;i++){
      if(i%2){
        digitalWrite(i, LOW);
      }else{
        digitalWrite(i, HIGH);
      }
    }
    delay(sleep);
  }
  for( int i = START_PIN;i<=END_PIN;i++){
        digitalWrite(i, LOW);
    }
  //mod 5
  for(int i = 0,a=START_PIN+1,b=END_PIN;i<=20;i++,a++,b--){
    if(a >= END_PIN)a=START_PIN+1;
    if(b <= 6)b=END_PIN+START_PIN;
  digitalWrite(a, HIGH);
  digitalWrite(b, HIGH);
  delay(sleep);
  digitalWrite(a, LOW);
  digitalWrite(b, LOW);
  delay(sleep);
  }
}