动态计算字符串表达式的结果

Question

有没有办法计算字符串表达式的结果,例如 mystring = "2*a+32-Math.Sin(6)"动态地知道a是我拥有的变量,可能有一些动态解决方案或使用System.Reflection

string mystring = "2*a+32-Math.Sin(6)"`;
decimal result = SomeMethod(mystring,3); // where a = 3 for example

Answer 1

如何让javascript计算你的表达式？

Type scriptType = Type.GetTypeFromCLSID(Guid.Parse("0E59F1D5-1FBE-11D0-8FF2-00A0D10038BC"));

dynamic obj = Activator.CreateInstance(scriptType, false);
obj.Language = "javascript";

var res = obj.Eval("a=3; 2*a+32-Math.sin(6)");

Answer 2

您可以通过以下方式使用数据表的计算SomeMethod方式：

       static decimal Somemethod(int val)
        {
            var result = (decimal)new DataTable().Compute(string.Format("2*{0}+32-{1}", val, Math.Sin(6)), "");
            return result;
        }

简单来说，您可以这样调用：

        result = Somemethod(3);

Answer 3

如果发现它工作正常，抱歉打扰，我想要的只是即时编译器。&这是我得到的

MessageBox.Show(Eval("5*3-Math.Sin(12) + 25*Math.Pow(3,2)").ToString());

public static object Eval(string sCSCode)
    {

        CodeDomProvider icc = CodeDomProvider.CreateProvider("C#");
        CompilerParameters cp = new CompilerParameters();

        cp.ReferencedAssemblies.Add("system.dll");
        cp.ReferencedAssemblies.Add("system.xml.dll");
        cp.ReferencedAssemblies.Add("system.data.dll");
        cp.ReferencedAssemblies.Add("system.windows.forms.dll");
        cp.ReferencedAssemblies.Add("system.drawing.dll");

        cp.CompilerOptions = "/t:library";
        cp.GenerateInMemory = true;

        StringBuilder sb = new StringBuilder("");
        sb.Append("using System;\n");
        sb.Append("using System.Xml;\n");
        sb.Append("using System.Data;\n");
        sb.Append("using System.Data.SqlClient;\n");
        sb.Append("using System.Windows.Forms;\n");
        sb.Append("using System.Drawing;\n");

        sb.Append("namespace CSCodeEvaler{ \n");
        sb.Append("public class CSCodeEvaler{ \n");
        sb.Append("public object EvalCode(){\n");
        sb.Append("return " + sCSCode + "; \n");
        sb.Append("} \n");
        sb.Append("} \n");
        sb.Append("}\n");

        CompilerResults cr = icc.CompileAssemblyFromSource(cp, sb.ToString());
        if (cr.Errors.Count > 0)
        {
            MessageBox.Show("ERROR: " + cr.Errors[0].ErrorText,
               "Error evaluating cs code", MessageBoxButton.OK,
               MessageBoxImage.Error);
            return null;
        }

        System.Reflection.Assembly a = cr.CompiledAssembly;
        object o = a.CreateInstance("CSCodeEvaler.CSCodeEvaler");

        Type t = o.GetType();
        System.Reflection.MethodInfo mi = t.GetMethod("EvalCode");

        object s = mi.Invoke(o, null);
        return s;

    }