C++, date string processing functions

dateProcessing.cpp

/*
* NOTE: I am not 100% sure these functions work as intended.  They may serve
*  as a useful place to start though if a problem involving data parsing needs
*  to be solved.
*/

// --------------------------------------------
// Constants
// --------------------------------------------
const char JAN[4] = "JAN";
const char FEB[4] = "FEB";
const char MAR[4] = "MAR";
const char APR[4] = "APR";
const char MAY[4] = "MAY";
const char JUN[4] = "JUN";
const char JUL[4] = "JUL";
const char AUG[4] = "AUG";
const char SEP[4] = "SEP";
const char OCT[4] = "OCT";
const char NOV[4] = "NOV";
const char DEC[4] = "DEC";

const int ZERO = 0;
const int ONE = 1;
const int TWO = 2;
const int THREE = 3;
const int FOUR = 4;
const int FIVE = 5;
const int SIX = 6;
const int SEVEN = 7;
const int EIGHT = 8;
const int NINE = 9;
const int TEN = 10;

// --------------------------------------------
// Function Prototypes
// --------------------------------------------
int dayStringtoInt(char character);
int monthStringToInt(char letter1, char letter2, char letter3);
int yearStringtoInt(char letter1, char letter2, char letter3, char letter4);

// --------------------------------------------
// Function Implementations
// --------------------------------------------

/**
* @brief Converts a single character into a number
*
* @details Given a character, checks if it can be converted to an integer and
*     converts in if possible.  Returns '-1' if the character cannot be 
*     converted.
*
* @param character: the character to convert
*
* @returns int: the integer value of the character.  Returns '-1' if the
*     character cannot be converted into an integer

*
* @note
*     . returns '-1' if the character cannot be converted into an integer
*/
int dayStringtoInt(char character)
{
  int result;

  if( character >= '0' && character <= '9' )
  {
    result = int(character - '0');
  }
  else
  {
    result = -1;
  }

  return result;
}


/**
* @brief Given 3 letters, attempts to determine the month
*
* @details Takes in 3 letters and tries to match them to a month.
*
* @param letter1: the first letter 
* @param letter2: the second letter
* @param letter3: the third letter
*
* @returns int: returns an int representing the month
*
* @note None
*/
int monthStringToInt(char letter1, char letter2, char letter3)
{
  char month[4] = { letter1, letter2, letter3, NULL_CHAR };
  int monthIndex = -1;

  // compare the month string given to each month of the year. If the string
  // matches up with a month, record the index of that month and return the val
  if( strComp(month, JAN) == ONE )
  {
    monthIndex = 0;
  }
  else if( strComp(month, FEB) == ONE )
  {
    monthIndex = 1;
  }
  else if( strComp(month, MAR) == ONE )
  {
    monthIndex = 2;
  }
  else if( strComp(month, APR) == ONE )
  {
    monthIndex = 3;
  }
  else if( strComp(month, MAY) == ONE )
  {
    monthIndex = 4;
  }
  else if( strComp(month, JUN) == ONE )
  {
    monthIndex = 5;
  }
  else if( strComp(month, JUL) == ONE )
  {
    monthIndex = 6;
  }
  else if( strComp(month, AUG) == ONE )
  {
    monthIndex = 7;
  }
  else if( strComp(month, SEP) == ONE )
  {
    monthIndex = 8;
  }
  else if( strComp(month, OCT) == ONE )
  {
    monthIndex = 9;
  }
  else if( strComp(month, NOV) == ONE )
  {
    monthIndex = 10;
  }
  else if( strComp(month, DEC) == ONE )
  {
    monthIndex = 11;
  }
  else
  {
    monthIndex = -1;
  }
  
  return monthIndex;
}


/**
* @brief Given 4 letters, converts them into an integer representing the year
*
* @details Takes in 4 letters and tries to match them to a month.
*
* @param letter1: the first letter 
* @param letter2: the second letter
* @param letter3: the third letter
* @param letter4: the fourth letter
*
* @returns int: returns an int representing the year
*
* @note None
*/
int yearStringtoInt(char letter1, char letter2, char letter3, 
                                char letter4)
{
  char yearString[5] = { letter1, letter2, letter3, letter4, NULL_CHAR };
  int index, total = ZERO;

  for( index = ZERO; index < FOUR; index++ )
  {
    total = total * TEN + int( yearString[index]) - '0';
  }

  return total;
}