CSC 2210, SPA 6: Ticketing

Problem Description

hall.zip contains the start of a program to read seating data for a small concert hall. The following input (available as in.1)

        1 $Jane
        2 Paula
        3 Eddie
        4 $Shawna
        5 $FriendlyGhost
        6 BookItNowTravel
        0 END
        5 8
          .  .  2  -  .  .  1  1
          3  3  6  6  6  6  6  6
          -  1  .  4  .  2  .  4
          .  .  .  .  .  .  .  .
          -  -  6  6  6  6  -  -
        r 0,1,2
        o 1,4
        r 3,6,5

first lists the patrons by id (1-6), terminated by the line 0 END. Next it captures the currently reserved seats. The 5 8 indicates the hall has 5 rows with 8 seating positions in each row. This is followed by the information for each row where

• A '.' indicates a seat that is open
• A '-' indicates a seat that cannot be used such as a seat in front of where wheel chairs will be placed
• A number indicating which patron has reserved that seat. Patron ids can be between 1 and 99, inclusive. If the patron name starts with $, this indicates the patron is a donor.

The hall seating is followed by a sequence of commands reflecting actions at the ticket booth. The 'r' command reserves seats; r 0,1,3 means reserving seat 1 in row 0 for patron #3. Both seats and rows start at 0. The 'o' commands open seats back up; o 1,4 means to open seat 4 in row 1.

The initial program contains skeleton code for reading the original seating, including a structure to hold the data for the hall (including a list of patrons). You will extend the program to read and process the 'r' and 'o' commands and print the final seating setup. Running the program on the above input will generate

        Original hall seating:
          .  .  2  -  .  .  1  1
          3  3  6  6  6  6  6  6
          -  1  .  4  .  2  .  4
          .  .  .  .  .  .  .  .
          -  -  6  6  6  6  -  -
        Reserving row 0, seat 1 for Paula
        Releasing row 1, seat 4 for BookItNowTravel
        Reserving row 3, seat 6 for FriendlyGhost

        Final hall seating:
          .  2  2  -  .  .  1  1
          3  3  6  6  .  6  6  6
          -  1  .  4  .  2  .  4
          .  .  .  .  .  .  5  .
          -  -  6  6  6  6  -  -

        Seats for donors:
        row 0, seat 6
        row 0, seat 7
        row 2, seat 1
        row 2, seat 3
        row 2, seat 7
        row 3, seat 6

This output is available as out.1. Note this program follows the model of generating output in a format that is similar to the input. There are one or two blank spaces before each seat including the first one on each row. The program also describes which seats are being reserved and opened. In an effort to make the changes more visible in this writeup, the seats that have changed status are marked in bold text. Your solution will not use bold output. The donors are listed by seat position starting at row 0 and seat 0. This list would be used to place small gifts before the performance.

The provided code checks for several errors:

• Specifying an invalid input file on the command line.
• Failing to provide all required seat status information.
• An illegal command (not r or o): "Illegal command 'x' (3 fields) in row 3, seat 12."

You are to check for the following additional errors. Sample messages are listed for each; you will need to follow these formats precisely:

• An illegal seat status: [status string].
• Attempting to reserve or open an invalid seat (negative or larger than is valid given this concert hall): "Failed request to release row 5, seat -1: illegal position." and Failed reservation request: row 1, seat 15 is not legal."
• Attempting to reserve a seat that is not open: "Failed reservation request: row 12, seat 7 not open."
• Attempting to open a seat that is not reserved: "Failed request to release row 2, seat 17: seat not taken."
• Referring to a nonexistent patron: "Bad patron id: 13."

When the program encounters one of these "additional" errors, it should exit immediately. You can call exit(0); to do this. (Often you would exit with a non-zero status, but esubmit will report that as an error.) Note that each error message ends with a period. Also note that only one error message is printed for each command when there is a problem. You can add additional checks, but they are not required.

Hints and further requirements

• CLion is the preferred way to build your project; let your instructor know if you cannot get started. Alternatively, you may be able to use the provided Makefile by typing

          make
  

  at the command prompt. Be sure to save all files before doing it! After it is built, to run your code on (say) in1.txt, type

          a.exe in1.txt
  

  or

          a.exe < in1.txt
  

• Code to read data has generally been provided, though you may need to make changes. Note that the scanf format

          " %s %d, %d\n"
  

  means skip any leading whitespace, read a string until a whitespace character is found, read a number, read a command, then another number, and finally the newline. scanf returns the number of elements read.
• The function call feof(stdin) returns true if the previous command read all input. Code to read and sum up all numbers in a file would be

          int sum = 0, x;
          while ( !feof(stdin) ) {
             if ( scanf("%d", &x) == 1 )
                sum += x;
          }
  

• The provided code uses enum values record the status of each seat. Enumerated values in C (and C++) work similarly to Java with the difference that the enumerated value can be stored in a regular int. The code

          int this_seat_status = BLOCKED;
          ...
          if ( this_seat_status == OPEN ) ...
  

  illustrates using these values. The declaration

          enum PatronStatus { GENERAL, DONOR, BLOCKED };
  

  effectively declares three constants with GENERAL having the value 0, DONOR having the value 1, and BLOCKED having the value 2. The code

          enum { ROWS = 20 };
  

  creates a constant with the value 20; this is one way to get named constants in C.
• The easiest way to read the seat status is to read it into a string. If a space is right before a %s item in a format string (such as scanf("%d %s", &int, status), then it skips any leading whitespace. So then you can compare the string against "-" or "." for the blocked or open cases. If the string is a number, you can use atoi to convert it to an integer:

          char num[] = "42";
          int value = atoi(num);
  

  sets value to 42. If the string starts with some other character, such as the % in one of the tests, atoi will return 0:

          strcpy(num, "%1");
          value = atoi(num);      // sets value to 0
  

  Since there is no patron with id 0, you can use this return value to check for invalid seat characters.
• You must write multiple functions to implement process_all_commands. Each function, including process_all_commands and main, must be limited to about 15 lines. This forces you to write multiple functions for this lab.

Submission

1. Ensure the system is fully implemented, including satisfying ALL TODOs. You can leave the TODOs in your code.
2. Ensure your name is at the top of each source file.
3. Ensure your code meets the coding standard, especially in documentation and avoiding magic numbers.
4. Submit tickets.c as main and submit hall.h and hall.c as additional files.

Starter

If your instructor sets it up, you can receive up to 5 bonus points for this assignment by submitting a solution which can read the following data:

        1 someone
        0 END
        3 3
        .  .  .
        -  -  -
        .  .  .

and displaying the concert hall with no donors. A full solution will also work on this, but you do not have to implement the full solution. Submit it to esubmit as mini6.

Test Data

• input1.txt, output1.txt
• input2.txt, output2.txt
• input3.txt, output3.txt
• input4.txt, output4.txt
• input5.txt, output5.txt
• input6.txt, output6.txt
• input7.txt, output7.txt
• input8.txt, output8.txt