Microsoft.CodeAnalysis.CSharp.Scripting - C#

Question

Microsoft.CodeAnalysis.CSharp.Scripting - C#

Hemanth B 886

Hi, I am using the nuget package Microsoft.CodeAnalysis.CSharp.Scripting for my expression evaluator in C#. Almost everything is getting evaluated except few, like "(1-32) * (5/9)" which is giving 0 as result and "(9/5)" which is giving 1 as result instead of 1.8. Why is this happening?
I am using this code:

    var result = CSharpScript.EvaluateAsync<double>("(1- 32) (5/9)").Result;

Also when I provide the input without brackets in between or at the end like (1- 32) (5/9, it is throwing an exception saying ")" expected. How do I automatically add necessary brackets?

AgaveJoe 31,341

The syntax is the same as if you typed the equation in the editor. I would use a decimal.

static async Task Main(string[] args)
{
    var results = await CSharpScript.EvaluateAsync<decimal>("(decimal)(1 - 32) * (9m/5m)");
    Console.WriteLine(results.ToString());
}

Double example

static async Task Main(string[] args)
{
    var results = await CSharpScript.EvaluateAsync<double>("(double)(1 - 32) * (9d/5d)");
    Console.WriteLine(results.ToString());
}

Lex Li 6,042 Reputation points

2021-09-12T15:57:44.677+00:00

The cause is that your code var result = CSharpScript.EvaluateAsync<double>("(1- 32) * (5/9)").Result let the runtime executes the expression of (1-32) * (5/9) first, and then convert the result to double. However, during the calculation of 5/9 the compiler already converts 5 and 9 to integers, so 5/9 gives you 0. Then the result of (1-32) * (5/9) is 0, whether converting to double or not. Similarly, 9/5 gives you 1. If your goal is to do calculation in double, the expression must be modified to something like (1-32) * (5/9d). More can be found in this guide. Such behaviors come from old programming languages such as C/C++, so don't be surprised.