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CSharp · Console

/Program.cs

using System;
using System.Data;
using System.Text.RegularExpressions;
using System.Xml;
					
public class Program
{
	public static void Main()
	{
		string input = "20 * (6+3) / ((4+6)*9)";
        Console.WriteLine(input);
        DataTable dt = new DataTable();
        Regex rx = new Regex(@"\([^()]*\)");
        string expression = input;
        while (rx.IsMatch(expression))
        {
	        expression = rx.Replace(expression, m => dt.Compute(m.Value, null).ToString(), 1);
	        Console.WriteLine(expression);
        }
        Console.WriteLine(dt.Compute(expression, null));
	}
}