// C# Eval Expression

// Doc: https://eval-expression.net/eval-execute

​

// @nuget: Z.Expressions.Eval

​

/*

### The parameters

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You have multiple different ways how you can pass your parameters. Furthermore, there is no best way to pass parameters as everything depends on your scenario and preference:

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1. `Eval.Execute<TResult>(string code)`: https://dotnetfiddle.net/4vOu2H

2. `Eval.Execute<TResult>(string code, object parameters)`: https://dotnetfiddle.net/wdLPTE

3. `Eval.Execute<TResult>(string code, params object[] parameters)`: https://dotnetfiddle.net/Q0gWZ3

​

---

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1 - In the case of `Eval.Execute<TResult>(string code)`, you cannot pass parameters directly, but you can always common technic such as string concatenation or [string interpolation](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/tokens/interpolated):**

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​

> NOTE: Be careful when using string concatenation (1b) and string interpolation (1c). In the same way, using this technique for SQL can lead to SQL Injection; using this technique with code can lead to Code Injection. So you should generally avoid this solution if you execute code from user input.

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See more: https://eval-expression.net/eval-execute

*/

​

using System;

using System.Collections.Generic;

using Z.Expressions;

​

public class Program

{

    public static void Main()

    {

        // - 1a. Hardcoding parameter value in the expression

        {

            var expression = "return new List<int>() { 1, 2, 3, 4, 5 }.Where(x => x > 1 && x < 5)";

            var list1a = Eval.Execute<List<int>>(expression);

            FiddleHelper.WriteTable("1a. Hardcoding parameter value in the expression", list1a);

        }

        // - 1b. Using string concatenation

        {

            var minValue = 1;

            var maxValue = 5;

            var expression = "return new List<int>() { 1, 2, 3, 4, 5 }.Where(x => x > "+ minValue +" && x < "+ maxValue +")";

            var list1b = Eval.Execute<List<int>>(expression);

​

            FiddleHelper.WriteTable("1b. Using string concatenation", list1b);

        }

        // - 1c. Using [string interpolation](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/tokens/interpolated)

        {

            var minValue = 1;

            var maxValue = 5;

            var expression = $"return new List<int>() {{ 1, 2, 3, 4, 5 }}.Where(x => x > {minValue} && x < {maxValue})";

            var list1c = Eval.Execute<List<int>>(expression);

​

            FiddleHelper.WriteTable("1c. Using [string interpolation](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/tokens/interpolated)", list1c);

        }

    }

}

​

​