C# Convert string to if condition

Question

Is it possible to convert string

"value > 5 && value <= 10" 

to if statement?

if (value > 5 && value <= 10)
{
   //do something
}

I have conditions stored as strings in DB, so it must be a dynamic conversion

Answer 1

Instead you can treat it as a javascript line and can get this done using Windows Script Engines, provided value is a real value instead of variable name.

 if(ScriptEngine.Eval("jscript", "value > 5 && value <= 10"))
   {
     //Your logic
   }

Or if its a variable then you can build a JS function like below to accomplish this:

using (ScriptEngine engine = new ScriptEngine("jscript"))
{
  string JSfunction =  "MyFunc(value){return " + "value > 5 && value <= 10" + "}";

  ParsedScript parsed = engine.Parse(JSfunction);
  if(parsed.CallMethod("MyFunc", 3))
  {  
   // Your Logic
  }
}

Answer 2

You could use Linq.Expression to build up the expression tree, the one you provided:

"value > 5 && value <= 10"

var val = Expression.Parameter(typeof(int), "x");
var body = Expression.And(
     Expression.MakeBinary(ExpressionType.GreaterThan, val, Expression.Constant(5)), 
     Expression.MakeBinary(ExpressionType.LessThanOrEqual, val, Expression.Constant(10)));

var lambda = Expression.Lambda<Func<int, bool>>(exp, val);
bool b = lambda.Compile().Invoke(6); //true
bool b = lambda.Compile().Invoke(11); //false

This is just an example to get some idea, still you need a smart way to parse and build the tree.