EquationSolver

Summary

This is a reusable component for solving equatios in C#.

Equations can be tokenised, validated (with actionable feedback if validation fails) and solved.

EquationSolver offers a very simple API, an equation can be validated and solved (with methods of getting feedback) in only 9 lines!

Supports

The following features are supported:

• Equation validation with feedback
• User defined constants
• Addition
• Subtraction
• Multiplication
• Division
• Exponent
• Brackets
• Binary and Unary "-" operators
• Decimal inputs
• JSON config file to add new operators or change operator symbols (if you wanted to do that for some reason)

Using

Add everything under the EquationSolver namespace to your project.

using EquationSolver;

Solving Equations

EqSolve offers several paths to solve an equation.

No Validation

This method is liable to throw unfriendly exceptions.

decimal result = EqSolve.solveEquation("(5*6)^2", false);

Validation with Exceptions

This method returns a decimal, but if validation fails it will throw a ValidationException containing the ValidationInstance.

try
{
  decimal result = EqSolve.solveEquation(equation, true);
}
catch (ValidationException e)
{
  ValidationInstance valInstance = e.validationInstance; 
}

Validation with SolveResult Object

This method returns a SolveResult object which contains a flag, the result or the ValidationInstance.

SolveResult solveResult = EqSolve.solveEquation(equation);
if(solveResult.solved) //success
{
  decimal result = solveResult.result; //extract result
}
else
{
  validationInstance valInstance = solveResult.validationInstance;
}

Validation

Validation is offered either as a part of equation solving or as an indepentant function. Validation checks that the equation is syntactically correct and returns a ValidationInstance object.

ValidationInstance valInstance = EqValidator.isValid(equation);

ValidationInstance

The ValidationInstance is the result of validation, it contains a flag for if the overall equation is valid and an ordered list of ValidationObjects.

ValidationObject

A ValidationObject represents an individual validation failure, for example 5+5+ would result in a ValidationObject containing the token of the second '+' with the message:

\+ at position 4 is invalid

Tokeniser

The tokeniser can also be used independantly of equation solving

TokenString ts = Tokeniser.tokenise("(5*6)^2");

The tokeniser will ignore whitespace

User Defined Constants

EquationSolver offers the ability to define and utilise constants in equations.

Defining Constants

Constants can be defined in config.js

Constants are formatted as key-value pairs.

  "constants": 
  [
    [ "UserConstantA", 50 ],
    [ "user_constant_B", 25 ]
  ]

Rules: A constant can be any sequence of characters that does not include [0-9], '.' or an operator.

Using Constants

Using a constant is as simple as writing it in the equation. Mind that is it case-sensitive!

decimal result = EquationSolver.EqSolve("UserConstantA * 2");

Closing Remarks

If you want to try utilising this in your own application, check program.cs for some addition usage examples!