Fastest way to check if string contains only digits

Question

I know a few ways how to check this. regex,int.parse,tryparse,looping.

can anyone tell me what is the fastest way to check?

the nee

Answer 1

Try this code:

bool isDigitsOnly(string str)
{
   try
   {
      int number = Convert.ToInt32(str);
      return true;
   }
   catch (Exception)
   {
      return false;
   }
}

Answer 2

Another approach!

string str = "12345";
bool containsOnlyDigits = true;
try { Convert.ToInt32(str); }
catch { containsOnlyDigits = false; }