UanMathEvaluator

What is it?

UanMathEvaluator is a simple (not necessarily lightweight) C# library targeting .NET Standard 2.0 that enables evaluation of multi-line mathematical expressions with support for function calls, variable assignments, and control flow like if, for, and while.

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How do I use it?

After referencing the DLL in your project, you can create and evaluate expressions like so:

UanMathEvaluator.Expression expr = new UanMathEvaluator.Expression("x + y");

Assign values to variables (type double):

expr.Variables["x"] = 1;
expr.Variables["y"] = 2;

Define custom functions that return a double:

expr.Functions["halve"] = new UanMathEvaluator.MathMethod()
{
    ArgumentCount = 1,
    Method = args => args[0].Value * 0.5d
};

expr.Functions["while"] = new UanMathEvaluator.MathMethod()
{
    ArgumentCount = 2,
    Method = args =>
    {
        // evaluates the first argument as a body type 
        while (args[0].Expression.Evaluate(vars, functions).Value != 0)
        {
            evalArgs[1].Expression.Evaluate(vars, functions);
        }
        return 1;
    }
};

Then evaluate the expression:

double result = expr.Evaluate(); // Returns 3

⚠️ Note: The parser strips all whitespace from expressions, which may affect variable or function names if spacing is relied on.

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What does the syntax look like?

Argument Types

Functions take one of two argument types:

• value — an expression that's immediately evaluated during parsing
• body — a block of code inside {} that’s only evaluated when called

General Syntax

You can use standard math expressions like:

x + y * sin(z)

You can also define variables, execute conditional logic, and write multi-line code:

x = 1;
y = 2;
if (x == 1,
  {
    z = 32
  },
  {
    z = 128
  });
z;

In this case, Evaluate() returns the value of z, as the final line determines the return value of the entire expression. It's good practice to explicitly return a final variable or result.

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Operators

The evaluator supports the following:

• Arithmetic operators: +, -, *, /, ^, %
• Logical operators: &&, ||
• Comparison operators: ==, !=, <, <=, >, >=

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if Function

Conditional blocks are written as:

if (condition : value, trueBlock : body, falseBlock : body);

Internally, any non-zero value is considered true; 0 is false.

Example:

if (x > 0,
  { y = 1 },
  { y = -1 });

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for Function

Loop blocks look like this:

for (iterations : value, block : body)

You can access the current iteration index using the variable iter.

Nested loops are supported. Each nested level uses iter1, iter2, iter3, and so on:

for (3, {
  for (2, {
    total = total + iter * iter1;
  });
});

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while Function

While loops are defined like this:

while (condition : body, block : body)

The block runs repeatedly until condition evaluates to 0. As with if, any non-zero value means true.

Example:

x = 5;
while ({ x > 0 }, {
  x = x - 1;
});
x;

This returns 0.

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