Simply try this
String math = (100 * 5 - 2).ToString();
I don't know, Why you want more complex? It's very easy ..
And if you want surely that,You can do that by using EvaluateExpression
public int EvaluateExpression(string math )
{
return Convert.ToInt32(math);
}
........................
String math = "100 * 5 - 2";
int result = EvaluateExpression(math );
Console.WriteLine(result );
See this discussions
Evaluating string "3*(4+2)" yield int 18
Update:
If those values came from input textbox, then write this way
String math = txtCalculator.Text.Trim();
int result = EvaluateExpression(math );
Console.WriteLine(result );
And also you can find out some pretty answer from this discussion
Is it possible to compile and execute new code at runtime in .NET?
Update 2:
Finally I have tried this sample for you :
My full code for class library
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text.RegularExpressions;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml.XPath;
public partial class _Default : Page
{
protected void Page_Load(object sender, EventArgs e)
{
String math = "100 * 5 - 2";
Console.WriteLine(Evaluate(math));
}
public static double Evaluate(string expression)
{
var xsltExpression =
string.Format("number({0})",
new Regex(@"([\+\-\*])").Replace(expression, " ${1} ")
.Replace("/", " div ")
.Replace("%", " mod "));
// ReSharper disable PossibleNullReferenceException
return (double)new XPathDocument
(new StringReader("<r/>"))
.CreateNavigator()
.Evaluate(xsltExpression);
// ReSharper restore PossibleNullReferenceException
}
}