How to use variables with regex?

Question

This is the input string: 23x^45*y or 2x^2 or y^4*x^3.

I am matching ^[0-9]+ after letter x. In other words I am matching

Answer 1

Try using this pattern for capturing the number but excluding the x^ prefix:

(?<=x\^)[0-9]+

string strInput = "23x^45*y or 2x^2 or y^4*x^3";
foreach (Match match in Regex.Matches(strInput, @"(?<=x\^)[0-9]+"))
    Console.WriteLine(match);

This should print :

45
2
3

Do not forget to use the option IgnoreCase for matching, if required.