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<WRAP><color red><fs 200%>Corning Community College</fs></color></WRAP>
<WRAP><fs 150%>ENGR1050 C for Engineers</fs></WRAP>
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======Project: LOOPS - MATH TABLE FUN (mtf1)======

=====Objective=====
To continue incorporating loops into our problem-solving repertoire, aiding us in displaying information related to various math tables.

=====Reading=====
In "The C Book", please read through Chapter 5.

=====Program=====
It is your task to enhance the program you wrote last week (**mtf0**) that will use loops and other programming concepts learned this far to automate the display of entire mathematical operation tables (addition, subtraction, multiplication, division, or remainder; as indicated by the user). This information is potentially of value to some of your letter division efforts in the pctX projects.

=====Specifications=====
Your program should:

  * have valid, descriptive variable names of length //no shorter than// 4 symbols
    * I will make an exception for the use of 'row'
  * prompt the user for the operation ('+' for addition, '-' for subtraction, '*' for multiplication, '/' for division, and '%' for remainder)
    * properly store this in a variable of type **char**
    * check for a literal '+', '-', '*', '/', or '%' symbol to determine operation to perform
      * if invalid input, display an error and exit with a non-zero value of 1
  * prompt for the starting row (0-9)
    * properly store this in a variable of type **unsigned char**
  * prompt for the ending row (0-9)
    * properly store this in a variable of type **unsigned char**
  * prompt for the starting column (0-9)
    * properly store this in a variable of type **unsigned char**
  * prompt for the ending column (0-9)
    * properly store this in a variable of type **unsigned char**
  * check to make sure starting column, row is less than or equal to the corresponding ending column, row
    * if not, display an error (to STDERR) and exit with non-zero status code of 2 (for row) or 3 (for column)
  * display the table, performing the indicated operation
    * display both row and column headers, in uniform fashion/formatting throughout
    * display each numerical value in organized, consistent fashion, assuming two-digit numbers
  * using a single return statement at the conclusion of the code, return a 0 indicating successful operation

Some additional points of consideration:
  * Note that the driving variables in your loops need to be at least of type **short int**, otherwise you may get a warning when you compile it.
  * Some results may be negative, allow for the display of negative values in your output.
  * with certain (not all) operations on certain values, you might end up with a mathematically impossible result. In these cases, check for and avoid performing the computation, instead displaying "NA" in its place.
  * Only the table (headers/dividers included)should be output to STDOUT. Everything else (the input prompts) should be displayed to STDERR.
  * For the math operations that are not associative, the row value is the one to be operated against (ie result=row-col).
  * To display a '%' character using fprintf, repeat it: %%. That will cancel the otherwise substitutive properties of the symbol in the context of fprintf.
=====Compiling=====
As we have been doing all along, use the following options to gcc when compiling:

<cli>
lab46:~/src/c4eng/mtf1$ gcc -Wall --std=gnu99 -o mtf1 mtf1.c
lab46:~/src/c4eng/mtf1$ 
</cli>

=====Execution=====

====Sample run using multiplication====
<cli>
lab46:~/src/c4eng/mtf1$ ./mtf1
Which operation: *
Starting Row (0-9): 4
Ending Row (0-9): 8
Starting Column (0-9): 1
Ending Column (0-9): 5
 * |  1  2  3  4  5
---+----------------
 4 |  4  8 12 16 20
 5 |  5 10 15 20 25
 6 |  6 12 18 24 30
 7 |  7 14 21 28 35
 8 |  8 16 24 32 40
lab46:~/src/c4eng/mtf1$ 
</cli>

The execution of the program is short and simple- obtain the input, do the processing, produce the output, and then terminate.

====Sample run using addition====
<cli>
lab46:~/src/c4eng/mtf1$ ./mtf1
Which operation: +
Starting Row (0-9): 5
Ending Row (0-9): 7
Starting Column (0-9): 2
Ending Column (0-9): 7
 + |  2  3  4  5  6  7
---+-------------------
 5 |  7  8  9 10 11 12
 6 |  8  9 10 11 12 13
 7 |  9 10 11 12 13 14
lab46:~/src/c4eng/mtf1$ 
</cli>

====Sample run using subtraction====

<cli>
lab46:~/src/c4eng/mtf1$ ./mtf1
Which operation: -
Starting Row (0-9): 2
Ending Row (0-9): 6
Starting Column (0-9): 1
Ending Column (0-9): 4
 - |  1  2  3  4
---+-------------
 2 |  1  0 -1 -2
 3 |  2  1  0 -1
 4 |  3  2  1  0
 5 |  4  3  2  1
 6 |  5  4  3  2
lab46:~/src/c4eng/mtf1$ 
</cli>

====Sample run using division====
<cli>
lab46:~/src/c4eng/mtf1$ ./mtf1
Which operation: /
Starting Row (0-9): 6
Ending Row (0-9): 9
Starting Column (0-9): 0
Ending Column (0-9): 4
 / |  0  1  2  3  4
---+----------------
 6 | NA  6  3  2  1
 7 | NA  7  3  2  1
 8 | NA  8  4  2  2
 9 | NA  9  4  3  2
lab46:~/src/c4eng/mtf1$ 
</cli>

====Sample run using remainder====
<cli>
lab46:~/src/c4eng/mtf1$ ./mtf1
Which operation: %
Starting Row (0-9): 5
Ending Row (0-9): 8
Starting Column (0-9): 1
Ending Column (0-9): 5
 % |  1  2  3  4  5
---+----------------
 5 |  0  1  2  1  0
 6 |  0  0  0  2  1
 7 |  0  1  1  3  2
 8 |  0  0  2  0  3
lab46:~/src/c4eng/mtf1$ 
</cli>
====Sample run with invalid operation given====
<cli>
lab46:~/src/c4eng/mtf1$ ./mtf1
Which operation: x
ERROR: Must specify '+', '-', '*', '/', or '%'.
lab46:~/src/c4eng/mtf1$ 
</cli>

====Sample run with invalid row configuration====
<cli>
lab46:~/src/c4eng/mtf1$ ./mtf1
Which operation: +
Starting Row (0-9): 7
Ending Row (0-9): 2
ERROR: Starting row is greater than ending row
lab46:~/src/c4eng/mtf1$ 
</cli>


=====Reference=====
In the C4ENG public directory, inside the **mtf1** subdirectory, will be a copy of my implementation (in executable form), which abides by the project specifications. Please compare its output against that of your implementation.

=====Submission=====
To successfully complete this project, the following criteria must be met:

  * Code must compile cleanly (no warnings or errors)
  * Output must be correct, and match the form given in the sample output above.
  * Code must be nicely and consistently indented
  * Code must be well commented
  * Do NOT double space your code. Group like statements together.
  * Output Formatting (including spacing) of program must conform to the provided output (see above).
  * Track/version the source code in a repository
  * Submit a copy of your source code to me using the **submit** tool.

To submit this program to me using the **submit** tool, run the following command at your lab46 prompt:

<cli>
$ submit c4eng mtf1 mtf1.c
Submitting c4eng project "mtf1":
    -> mtf1.c(OK)

SUCCESSFULLY SUBMITTED
</cli>

You should get some sort of confirmation indicating successful submission if all went according to plan. If not, check for typos and or locational mismatches.

What I'll be looking for:

<code>
78:mtf1:final tally of results (78/78)
*:mtf1:proper error checking and status reporting performed [13/13]
*:mtf1:correct variable types and name lengths used [13/13]
*:mtf1:proper output formatting per specifications [13/13]
*:mtf1:runtime tests of submitted program succeed [13/13]
*:mtf1:no negative compiler messages for program [13/13]
*:mtf1:code is pushed to lab46 repository [13/13]
</code>

Additionally:
  * Solutions not abiding by spirit of project will be subject to a 25% overall deduction
  * Solutions not utilizing descriptive why and how comments will be subject to a 25% overall deduction
  * Solutions not utilizing indentation to promote scope and clarity will be subject to a 25% overall deduction
  * Solutions not organized and easy to read are subject to a 25% overall deduction