Convert string decimal to int

Question

I have a string "246246.246" that I'd like to pass to the IConvertable interface, ToInt16, ToInt32, ToIn64. What is the best way to parse a string with decimal places to an integer?

This is a solution, but is there a better solution?

string value = "34690.42724";
Convert.ToInt64(Convert.ToDouble(value));

Answer 1

To do this discounting rounding you could do:

Convert.ToInt64(Math.Floor(Convert.ToDouble(value)));

If you need to round you could replace Math.Floor with Math.Round.

Edit: Since you mentioned in a comment that you'll be rounding:

Convert.ToInt64(Math.Round(Convert.ToDouble(value)));

If you have to worry about localization/globalization then as @xls said you should apply a CultureInfo in the conversions.

Edit 2: Alternative method using a string function (not terribly elegant IMO - maybe it could be elegantized with a predicate function):

Convert.ToInt64(value.Substring(0, value.IndexOf('.') > 0 ? value.IndexOf('.') : value.Length));

Answer 2

If you are really worry about accuracy but not about speed then decimal type would be better.

(long)Math.Round(decimal.Parse(value));

Answer 3

Assuming this string comes from user input, you probably want to catch number styling. Run it through a reusable function like so...

int? ConvertToNumber(string value)
{
   if (value == string.Empty) return null;

   try
   {
       var dec = decimal.Parse(value,
           NumberStyles.AllowDecimalPoint |
           NumberStyles.Number |
           NumberStyles.AllowThousands);

       return (int)Math.Round(dec);
   }
   catch (Exception ex)
   {
       Console.WriteLine("Please input a number.");
       return null;
   }
}

Answer 4

You should not have to Round the value as ToInt64(double) returns the rounded version already

        string value = "246246.246";
        Convert.ToInt64(Convert.ToDouble(value));