C# 根据用户输入的字符串 表达式进行动态计算

动态函数生成 ：

/// <summary>
/// 计算公式，参数名字符，传入的参数
/// </summary>
/// <param name="expression"></param>
/// <param name="paramsNames"></param>
/// <return

   
 private object CalCulate(string expression, string[] paramsNames, object[] parameters)
        {
            string className = "Calc";
            string methodName = "Run";
            expression = expression.Replace("/", "*1.0/");
            CompilerParameters paras = new CompilerParameters();
         
            paras.GenerateInMemory = true;
            StringBuilder classSource = new StringBuilder();
            string paramstr= "";
            if (paramsNames.Length>0)
            {
                foreach (var item in paramsNames)
                {
                    paramstr += $"double {item} ,";
                }
            }
            if (paramstr.Length>0)
            {
                paramstr = paramstr.Substring(0, paramstr.Length - 1);
            }
            
            classSource.Append("public class " + className + "\n");
            classSource.Append("{\n");
            classSource.Append(" public object " + methodName + $"({paramstr})\n");
            classSource.Append(" {\n");
            classSource.Append(" return " + expression + ";\n");
            classSource.Append(" }\n");
            classSource.Append("}");

            //编译代码
            CompilerResults result = new CSharpCodeProvider().CompileAssemblyFromSource(paras, classSource.ToString());
            if (result.Errors.Count > 0)
            {
                string msg = $"Formula({className})\n";
                foreach (CompilerError item in result.Errors)
                {
                    msg += item.ToString() + "\r\n";
                }
                throw new Exception(msg);
            }

            object reobj = 0 ;
            try
            {
                //获取编译后的程序集。 
                Assembly assembly = result.CompiledAssembly;

                //动态调用方法。 
                object eval = assembly.CreateInstance(className);
                MethodInfo method = eval.GetType().GetMethod(methodName);
                reobj = method.Invoke(eval,   parameters);
           
            }
            catch (Exception ex)
            {
                throw ex;

            }
            return reobj;
        }

进行计算测试

 try
            {
                string expression = this.textBox1.Text;
                  expression ="1*2+3*4";
                  expression ="1*2+3*4+k*10+j*5";
                  expression ="1*2+3*4+k*10";
                  expression ="1*2+3*4+j*10";
                object res = CalCulate(expression, new string[] { "j", "k" }, new object[] { 10, 20 });
                  double.TryParse(res,out double resValue)
                this.textBox2.Text = resValue.ToString();
            }
            catch (Exception ex)
            {

               
            }