check string is numeric or not in c# .net

int result;
if (int.TryParse(myString, out result))
{
    //ok, do something
}
else
{
    //not an int
}

int n;
        bool isNumeric = int.TryParse("123a", out n);

using System.Text.RegularExpressions;

Regex regex = new Regex(@"^[0-9]+$");

private bool IsInteger(string str)
{
	try
	{
		if (String.IsNullOrWhiteSpace(str))
                {
			return false;
		}
		if(!regex.IsMatch(str))
		{
			return false;
		}
		
		return true;
                
	}
	catch(Exception ex)
	{
		MessageBox.Show(ex.Message);
	}
	
	return false;
	
}

int result;
myString="123";
if (int.TryParse(myString, out result))
{
    Console.WriteLine("String is numeric");
}
else
{
    Console.WriteLine("String is non numeric");
}