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

In “The C Book”, please read through Chapter 5.

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.

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.

As we have been doing all along, use the following options to gcc when compiling:

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

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$ 

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

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$ 

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$ 

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$ 

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$ 

lab46:~/src/c4eng/mtf1$ ./mtf1
Which operation: x
ERROR: Must specify '+', '-', '*', '/', or '%'.
lab46:~/src/c4eng/mtf1$ 

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$ 

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.

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:

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

SUCCESSFULLY SUBMITTED

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:

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]

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