C# Code:

/// <summary>
/// 程序说明：C#动态编译计算表达式的值，是通过System.CodeDom.Compiler命名空间下的相关类来实现的,如：CSharpCodeProvider类。步骤如下：
/// 1.将表达式封装成为可编译的C#代码；
/// 2.动态编译C#代码，生成Assembly程序集。
/// 3.使用.NET反射调用方法计算表达式的值。
/// </summary>
public static class CodeDomExpression
{
   
   public static decimal Calculate(string expression)
   {
      try
      {
         return decimal.Parse(DoCalculate(expression).ToString());
      }
      catch
      {
         return 0;
      }
   }
   
   /// <summary>
   /// 计算表达式的值
   /// </summary>
   /// <param name="expression">表达式</param>
   /// <returns></returns>
   private static object DoCalculate(string expression)
   {
      string code = DoWrapCode(expression);
      
      CSharpCodeProvider csharpCodeProvider = new CSharpCodeProvider();
      CompilerParameters compilerParameters = new CompilerParameters();
      compilerParameters.CompilerOptions = "/t:library";
      compilerParameters.GenerateInMemory = true;
      
      //编译C#源码,稍有停顿！
      CompilerResults compilerResults = csharpCodeProvider.CompileAssemblyFromSource(compilerParameters, code);
      if (compilerResults.Errors.Count > 0)
      throw new Exception("编译表达式出错！");
      
      Assembly assembly = compilerResults.CompiledAssembly;
      Type type = assembly.GetType("ExpressionCalculate");
      MethodInfo method = type.GetMethod("Calculate");
      return method.Invoke(null, null);
   }
   
   /// <summary>
   /// 封装C#代码
   /// </summary>
   /// <param name="expression"></param>
   /// <returns></returns>
   private static string DoWrapCode(string expression)
   {
      string code = @"
      using System;
      public class ExpressionCalculate
      {
         public static object Calculate()
         {
            return {0};
         }
         }";
         
         return code.Replace("{0}", expression);
      }
      
   }
   
   //来源:C/S框架网(www.csframework.com) QQ:23404761