将负字符串十进制值转换为C＃中的double

Question

I want to convert a value in string format like -14.3 to double.

I am currently using Convert.ToDouble() to convert positive values to double but in case of negative decimal values it returns unexpected results. For -14.3 it returns -143 . So need some help in this regard

 private double getDouble(string Value)
        {
            double result = 0;
            try
            {               
                result = Convert.ToDouble(Value);                
            }
            catch (Exception)
            {
                result = 0;
            }

            return result;
        }

    }

Answer 1

You need to use NumberFormatInfo to specify the characters used for the negative sign and the decimal separator.

var format = new NumberFormatInfo();
format.NegativeSign = "-";
format.NumberDecimalSeparator = ".";

var negativeNumber = Double.Parse("-14.3", format); // -14.3
var positiveNumber = Double.Parse("352.6", format); // 352.6

See the code in action on repl.it .

Answer 2

Instead of using Convert.ToDouble function, use:

public static double mtdGetDouble(string Value)
{
    if (Value == "" || Value == "-") return 0;
    else return Convert.ToDouble(Value);
}

(It's my Style...)

Answer 3

If you want to use Double.TryParse with NumberFormatInfo you need to specify NumberStyles.AllowDecimalPoint and NumberStyles.AllowLeadingSign .

var format = new NumberFormatInfo();
format.NegativeSign = "-";
format.NumberNegativePattern = 1;
format.NumberDecimalSeparator = ".";

double negativeNumber;
Double.TryParse("-14.3", NumberStyles.AllowDecimalPoint | NumberStyles.AllowLeadingSign, format, out negativeNumber); // -14.3
double positiveNumber;
Double.TryParse("352.6", NumberStyles.AllowDecimalPoint | NumberStyles.AllowLeadingSign, format, out positiveNumber); // 352.6