Exception while parsing negative double numbers in C#

Question

I'm coding a peace of code that extracts some data from a DB. And the problem is that I want to convert a negative number string "−2.8" to a double. Pretty easy, I thought. I tried first with:

var climateString = "−2.8";
var number = double.Parse(climateString);

With this result:

An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll

So I thought again, searched on google, and got new answer:

var climateString = "−2.8";
var styles = NumberStyles.AllowParentheses | NumberStyles.AllowTrailingSign |NumberStyles.Float | NumberStyles.AllowDecimalPoint;
var rit = double.Parse(climateString, styles);

Epic fail again:

An unhandled exception of type 'System.FormatException' occurred in mscorlib.dll

I thought again, I cannot be so stupid as not to know how to do such a simple task. I tried this:

 var climateString = "−2.8";
 var doue = Convert.ToDouble(climateString, CultureInfo.InvariantCulture);

Yes, the exact same exception again. I started looking a the number, and, I realized on the negative sign. Look this number carefully "−2.8" this is not a negative number this. This is a negative number "-2.8". Look at those signs again "----- −−−−−" not the same. Parsing a string with a different sign character throws an exception : S. So, anyone has an idea, how to parse it elegantly to a double number in C#? Thak you!

Answer 1

Substitute a hyphen for the dash:

var climateString = "−2.8".Replace ("−", "-");
var number = double.Parse(climateString);

(You might want to be on the lookout for other strange characters coming out of that database, though.)

Answer 2

Proper way to do it:

var climateString = "−2.8"; 

var fmt = new NumberFormatInfo();
fmt.NegativeSign = "−";
var number = double.Parse(climateString, fmt);    

Answer 3

Might be an old post but for anyone else reading this...

You have NumberStyles.AllowTrailingSign, that should probably be NumberStyles.AllowLeadingSign otherwise it will not accept a - sign anyways.

Answer 4

I would suggest to use TryParse instead of Parse method because it gently handle you error if any.

Code -

var test1 = "-123.95"; decimal result; decimal.TryParse(test1, out result);

you'll get parsed double value in result.

Answer 5

Try this:

decimal.TryParse(number, NumberStyles.AllowExponent | NumberStyles.AllowDecimalPoint | NumberStyles.AllowLeadingSign, CultureInfo.InvariantCulture, out decimal numberOut)