Clash Royale CLAN TAG#URR8PPP

evaluate relational operator from a string

I have relational expressions stored in a database, that i have as strings in an iOS app. I would like to evaluate the conditions within the strings in C#, similar to the logic in the following psudo code:

string str1= "x > 0";
string str2= "y < 1";

int x = 1;
int y=0;

if(str1 && str2)

//do stuff



enum

2 Answers
2

If the expressions are simple like the one in the example, then you can simply parse them. But if you have more complex expressions in mind, then I recommend taking a look at C# Expression Trees. The documentation does a good job of explaining it.

A much easier method would be to use library like: https://github.com/davideicardi/DynamicExpresso

Use Afk Expression Library (Afk link)
and try following code it will solve your problem as I sorted out.

Required NameSpace

using Afk.Expression;


Your code for sending expression as string to library evaluator

string str1 = "x > 0";
string str2 = "y < 1";

int x = 10;
int y = 0;
var st1=str1.Replace("x",x.ToString());
var st2 = str2.Replace("y", y.ToString());
if (Eval(st2) && Eval(st1))

//checked



Eval Method evaluate mathematical and conditional expression

bool Eval(string st)

ExpressionEval eval = new ExpressionEval(st);
return Convert.ToBoolean(eval.Evaluate().ToString());



As well read for more other libraries that you can utilize for your as such problems.

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.