#define ALLOW_INSTRUCTOR_CODE
/***************************************************************************
 ***************************************************************************
 ****** BEFORE BEGINNING OR TURNING IN THIS EXERCISE IT IS  EXTREMELY ******
 ****** IMPORTANT THAT YOU READ, FULLY UNDERSTAND, AND ADHERE TO  THE ******
 ****** REQUIREMENTS STATED  IN  THE  DOCUMENT  TITLED,   "ASSIGNMENT ******
 ****** SUBMISSION REQUIREMENTS", DOWNLOADABLE FROM  THE  COURSE  WEB ******
 ****** SITE.                                                         ******
 ***************************************************************************
 **************************************************************************/



/***************************************************************************
 ************* C/C++ Programming 2:  Assignment 8 - Exercise 2 *************
 ******** BEGIN EXERCISE REQUIREMENT - THIS MUST BE A "C++" PROGRAM ********
 ***************************************************************************

   (5 points)  Write functions OpenFile and DisplayColumns:

      OpenFile syntax:
         void OpenFile(const char *fileName, ifstream &inFile);
      Parameters:
         fileName - a pointer to the name of the file to be opened
         inFile -   a reference to the ifstream object to be used to open
                    the file
      Synopsis:
         Opens the file named in <fileName> in the read-only text mode
         using the <inFile> object.  If the open fails an error message
         is output to cerr and the program is terminated with an error
         exit code.
      Return:
         void if the open succeeds; otherwise, the function does not return.

   
      DisplayColumns syntax:
         void DisplayColumns(const char *sFirstColumn,
                             const char *sLastColumn, ifstream &inFile);
      Parameters:
         sFirstColumn -  a pointer to a string representing a starting
                         column number.
         sLastColumn  -  a pointer to a string representing an ending
                         column number.
         inFile -        a reference to an ifstream object representing
                         an open text file
       Synopsis:
         Displays the contents of each line in the file in <inFile> starting
         with the character in <sFirstColumn> and ending with the character
         in <sLastColumn>.  If <sFirstColumn> is beyond the last column of a
         line a blank line is displayed.  The display of any line ends when
         the line itself ends, even if <sLastColumn> is beyond that point.
         By definition, the first column of any line is 1, not 0.  An empty
         file is simply closed and ignored.
      Return:
         void


   * Specify the column numbers and file name on the command line using the
     format:  first#  last#  fileName
   * Assume no line will contain more than 511 characters.
   * Assume every character on each line, including the tab, occupies one
     column.
   * Do not attempt to store the entire contents of the file.     
   * Test the program three times using file "TestFile1.txt", downloaded
     from the course web site and the following command line argument
     lists:

         2  23  TestFile1.txt
        36  36  TestFile1.txt
        61  80  TestFile1.txt


   Examples:  For a file named ABCD containing four lines, labeled below
              as "1st line", "2nd line", "3rd line", and "4th line":

      Column# MSD:  0000000001111111111222222222233333333334444444444555...   
      Column# LSD:  1234567890123456789012345678901234567890123456789012...
      1st line:     This is a typical line in a file.
      2nd line:     Another one.
      3rd line:        Short!     Long!
      4th line:     ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789
       
      Command line:    13  25  ABCD
         1st display:  pical line in
         2nd display:
         3rd display:    Long!
         4th display:  MNOPQRSTUVWXY
      
      Command line:    34  60  ABCD
         1st display:
         2nd display:
         3rd display:
         4th display:  789

    Hint:
      * Place input test file "TestFile1.txt" in the appropriate default
        location described in the "FILE LOCATION QUESTIONS AND ANSWERS"
        section of the "ASSIGNMENT SUBMISSION REQUIREMENTS" document.
 
 ***************************************************************************
 ************************ END EXERCISE REQUIREMENT *************************
 **************************************************************************/



/***************************************************************************
 * BEFORE PRINTING THIS ASSIGNMENT  TO  TURN  IN, DELETE  THIS  COMMENT  AND
 * EVERYTHING ABOVE IT.
 **************************************************************************/

/*
 * TODO:
 *   REPLACE THIS COMMENT WITH YOUR TITLE BLOCK.
 */

/*
 * TODO:
 *    REPLACE THIS COMMENT WITH YOUR C++ CODE, PLUS  ANYTHING  NECESSARY  TO
 *    SUPPORT MY TEST CODE BELOW.  DO NOT INCLUDE ANY UNNEEDED HEADER FILES!
 */

/***************************************************************************
 * BEFORE PRINTING THIS ASSIGNMENT  TO  TURN  IN, DELETE  THIS  COMMENT  AND
 * EVERYTHING BELOW IT.
 **************************************************************************/

/*
 ***** Change nothing below this comment without instructor permission. ****
 * Everything that follows was written to help test/verify your code.  You
 * do not need to understand the details of my code to write yours!
 */
#ifdef ALLOW_INSTRUCTOR_CODE
int main(int argc, char *argv[])
{
   const int ARGUMENTS_EXPECTED = 4;           // command line args expected

   if (argc != ARGUMENTS_EXPECTED)             // number of cmd. line args
   {
      cerr << "Specify: firstColumn lastColumn fileName";
      exit(EXIT_FAILURE);
   }

   ifstream inFile;

   OpenFile(argv[3], inFile);                  // open the file
   DisplayColumns(argv[1], argv[2], inFile);
   inFile.close();                             // close input file

   return EXIT_SUCCESS;
}
#endif