C#: best and safe way to convert nullable string to int code example

Example: parsing string to int without format exception c#

using System; namespace ConvertStringtoNumber{    public class Program    {        public static void Main(string[] args)        {            string s1="10";            string s2="20";            int num1=0,num2=0;            Int32.TryParse(s1, out num1);            Int32.TryParse(s2, out num2);             int add=num1+num2;            Console.WriteLine("Addition of 10 and 20 is {0}",add.ToString());         }    }}