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Assignment 1 – Spring 2017 Page 1

Faculty of Engineering and Information Technology

School of Software

31927 - Applications Development with .NET

32998 - .NET Applications Development

SPRING 2018

ASSIGNMENT 1 SPECIFICATION

DUE DATE – Monday, 17

th September 2018

This assignment is worth 25% of the total marks

Requirement Assignment Documentations

This assignment is split into two documents.

1. Assignment Specification. This document contains the specification for what

you will be required to do.

2. Assignment Addendum. This document contains all other details regarding

the assignment, including assignment submission and the assessment

scheme.

Requirement

In this assignment you are to prepare a C# program that will act as a simple

equation solver. The equation solver will be run from the command line and will only

work with integer numbers, a single variable (X) and the following arithmetic

operators: + - * /.

For example, if the C# program is compiled to Equ.exe, the following demonstrates

how it will appear in the command line:

calc 3X + 5 = 8

X = 1

In the command line, the argument is entered as the “calc” keyword followed by a

space and followed by a sequence of numbers, variables, and operators, such as:

calc <Equation formula>

Hitting the enter key will cause the program to evaluate the arguments and print the

result as one or more numbers separated by “,”:

X=<result>.

The console should remain open and allow the user to continue to enter equations to

be solved.

Assignment 1 – Spring 2017 Page 2

The program must follow the math rules of solving equations with 1 variable type (i.e.

linear and quadric style equations). For example:

2X – 1 = 0

3X + 8X = 33

4X - 7 = 8X - 5

X / (x+12) = 1 / 13

The program must follow the usual laws of arithmetic which says:

1. The * / and % operators must all be evaluated before the + and –

operators.

2. Operators must be evaluated from left to right.

For example, using Rule 1

X = 2 + 4 * 3 – 6

Becomes

X = 2 + 12 – 6

Which results in

X = 8

If we did not use Rule 1 then 2+4*3–6 would become 6*3–6 and then 18–6 and

finally 12. This is an incorrect result.

If we do not use Rule 2 then the following illustrates how it can go wrong

4*5%2

Going from left to right we evaluate the * first, which reduces the expression to 20%2

which becomes 0. If we evaluated the % first then the expression would reduce to

4*1 which becomes 1. This is an incorrect result. Remember, we are using integer

mathematics when doing our calculations, so we get integer results when doing

division. For example:

calc X = 20 / 4

X = 5

Also note that we can use the unary + and – operators. For example:

calc X = -5 / +2

X = -2

Your program must also check to make sure the command line argument is correct

and handle the equation parts. If not your program must generate an appropriate

error message and then terminate. For example:

calc X = - 3 + 4 / 6 (spaces represent splitters between numbers and operators)

Becomes X = -3 + 4 / 6

calc X = 3 + 4 / 6 + (space after+)

Becomes X = 3 + 4 / 6 + 0 (replace by 0)

Becomes X = 3 + 4 / 6

calc X = 3 + + + 4 - 6 (operation elimination)

Assignment 1 – Spring 2017 Page 3

Becomes X = 3 + 4 - 6

calc X = 3 - - - 8X - 4

Becomes X = 3 - 8X - 4

calc X + 3 + 6 + 3333333333333

Invalid Input (this is not equation and invalid as well)

calc X^2 = 2121212121 + 2020202020

Out of Integer Range

calc X = 4 / 0

Division by zero

Program Hints

1. Getting your program to solve expressions that only use the + and –

operators is fairly easy. I would suggest you get your program working at this

level before attempting to get it to work with the other operators.

2. You will find this problem much easier to solve if you application has a good

design concept; create a generic input that takes all parameters and

operations and break it down into smaller methods responsible for

validations, aggregations and calculations. For example, enumerate the

possible operations and then have a method that solves (number operator

number). Also have a method that gets the number from a string and another

that gets the operator from a string. Also note that splitting your code up will

give you a better design mark.

Assignment Objectives

The purpose of this assignment is to demonstrate competence in the following

skills.

• Problem solution

• Employ basic mathematic skills to develop C# program

• Program design

• Array and string manipulation

• Command line arguments

• Creating Object Oriented methods in C#

These tasks reflect all the subject objectives.

The solution of this assignment will take between 200 and 300 lines of code,

including white space (blank lines) comments, etc. The exact number will

depend on how the students solve the task. As part of your subject workload

assessment, it is estimated this assignment will take more than 30 hours to

complete.