Use regualr expression to check: Is it an Unsigned Integer

   
 
using System;
using System.Data;
using System.Text.RegularExpressions;

class Class1{
        static void Main(string[] args){
      string IsNotNum = "111west";
      string IsNum = "  +111  ";
      string IsFloat = "  23.11  ";
      string IsExp = "  +23 e+11  ";
      
      Console.WriteLine(IsUnsignedIntegerRegEx(IsNum));    // True
      Console.WriteLine(IsUnsignedIntegerRegEx(IsNotNum));  // False
      Console.WriteLine(IsUnsignedIntegerRegEx(IsFloat));    // False
      Console.WriteLine(IsUnsignedIntegerRegEx(IsExp));    // False
        }
    public static bool IsUnsignedIntegerRegEx(string str)
    {
      str = str.Trim();
      return (Regex.IsMatch(str, @"^+?d+$"));
    }
    
}