Convert String to Integer [duplicate]

Answer 1

Rather than using Convert.ToInt32(string) you should consider using Int32.TryParse(string, out int) instead. The TryParse methods are there to help deal with user-provided input in a safer manner. The most likely cause of your error is that the substring you are returning has an invalid string representation of an integer value.

string str = line.Substring(0,1);
int i = -1;
if (Int32.TryParse(str, out i))
{
   Console.WriteLine(i);
}