我如何只读取包含数字的文本文件的第一行，并进行数学运算？

Question

I have a text file which contains a list of numbers. the first line is 5.5, the second line is 8 third line is 13 and so on. Each text file generates a list of number different each time but I'm only concentrating on the first line which in this case is 5.5, here is my code

                StreamReader FileFav = new StreamReader(BettingFileFav);
                StreamReader FileOdds = new StreamReader(BettingFileOdds);
                StreamReader FileResult = new StreamReader(BettingFileResult);
                FavLine = FileFav.ReadLine();
                OddsLine = FileOdds.ReadLine();
                ResultLine = FileResult.ReadLine();
                int BetAmount = 10;

                if (FavLine.Contains("Yes"))
                {
                    int a = Convert.ToInt16(OddsLine);
                    double c = ((double)a * BetAmount);
                    string myString = c.ToString("#.##");
                    MessageBox.Show("Won £" + myString);
                }
                else
                {
                    MessageBox.Show("Lost -£" + BetAmount); 
                }

the line of text it has read reads 5.5 so I am trying to get the answer 55.50. I get an error code

Additional information: Input string was not in a correct format.

I'm using the MessageBox.Show to see if it works then migrating the result to a file which I will be using later.

Can anybody help?

Answer 1

As was pointed out in the comments, you are trying to convert a floating point number to an integer, which is not accepted by Convert.ToInt16 . The function requires the string to represent an actual signed integer value that fits within 16 bits, as described in the documentation .

However based on your following calculation, what you really want to do is convert the string to a double straight away, so you should use Convert.ToDouble instead.

So the lines

int a = Convert.ToInt16(OddsLine);
double c = ((double)a * BetAmount);

should become

double a = Convert.ToDouble(OddsLine);
double c = (a * BetAmount);