/**
 * Program: find out is the user typed in a leap year. The code assumes
 * the user is not an idiot and only types in numbers that are a valid
 * year.
 * Author: Dr. Purdum, Aug. 7, 2012
 **/
void setup()
{
  Serial.begin(9600);
}
void loop()
{
  if (Serial.available() > 0) {
    int bufferCount;
    int year;
    char myData[20];
    bufferCount = ReadLine(myData);
    year = atoi(myData);
    Serial.print("Year: ");
    Serial.print(year);
    if (IsLeapYear(year)) {
      Serial.print(" is ");
    } 
    else {
      Serial.print(" is not ");
    }
    Serial.println("a leap year");
  }
}
// Convert to int
/*****
 * Purpose: Determine if a given year is a leap year
 * Parameters:
 * int yr		
 * The year to test
 * Return value:
 * int 		
 * 1 if the year is a leap year, 0 otherwise
 *****/
int IsLeapYear(int yr)
{
  if (yr % 4 == 0 && yr % 100 != 0 || yr % 400 == 0) {
    return 1;	 // It is a leap year
  } 
  else {
    return 0;	
    // not a leap year
  }
}
/*****
 * Purpose: Read data from serial port until a newline character is read ('\n')
 * Parameters:
 * char str[]
 * character array that will be treated as a nul-terminated string
 * Return value:
 * int
 * the number of characters read for the string
 * CAUTION: This method will sit here forever if no input is read from the serial
 * port and no newline character is entered.
 ****/
int ReadLine(char str[])
{
  char c;
  int index = 0;
  while (true) {
    if (Serial.available() > 0) {
      c = Serial.read();
      if (c != '\n') {
        str[index++] = c;
      } 
      else {
        str[index] = '\0'; // null termination character
        break;
      }
    }
  }
  return index;
}