将字符串转换为Double C＃

Question

I have a field in DB which is float. My application is WindowsForm. I need to convert the value in textbox of the format 43.27 to double. When I do this COnvert.ToDouble(txtbox.Text) I get exception saying input string is wrong format. How to rectify this issue

Answer 1

Try specifying a culture when parsing:

// CultureInfo.InvariantCulture would use "." as decimal separator
// which might not be the case of the current culture
// you are using in your application. So this will parse
// values using "." as separator.
double d = double.Parse(txtbox.Text, CultureInfo.InvariantCulture);

And to handle the error case for gracefully instead of throwing exceptions around you could use the TryParse method:

double d;
if (double.TryParse(txtbox.Text, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out d))
{
    // TODO: use the parsed value
}
else
{
    // TODO: tell the user to enter a correct number
}

Answer 2

When you want to convert a string to number, you need to be sure which format does the string use. Eg in English, there is a decimal point (“43.27”), while in Czech, there is a decimal comma (“43,27”).

By default, the current locale is used; if you know the number uses the English conversion, you need to specify the culture explicitly, eg

Convert.ToDouble(txtBox.Text, CultureInfo.InvariantCulture);