Convert string to double: input string was not in a correct format

Question

I am getting some values from my Arduino over the serial port. The data has the format: "value1,value2,value3\r" as a string.

Example: "4.5,550.0,0.02\r"

I can recieve and separate the values but when I try to convert them to double I get the following exception

"input string was not in a correct format"`.

double Battery = 0, Voltage = 0, Current = 0;

private void serialPort1_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
    string data = serialPort1.ReadLine();
    string bv = data.Substring(0, data.IndexOf(",") - 1);
    data = data.Substring(data.IndexOf(",") + 1);
    string v0 = data.Substring(0, data.IndexOf(",") - 1);
    data = data.Substring(data.IndexOf(",") + 1);
    string i = data;

    double batteryVoltage = Convert.ToDouble(bv);
    double V0 = Convert.ToDouble(v0);
    double I = Convert.ToDouble(i);

    Battery = batteryVoltage;
    Voltage = V0;
    Current = I;

}

Solution

Two things are a problem here. First, the conversion may fail because of regional settings (invalid decimal point character), so use CultureInfo.InvariantCulture from System.Globalization namespace as an additional parameter. Second thing, you are cutting off one character from your substrings, so remove -1.

string data = "4.5,550.0,0.02\r";
string bv = data.Substring(0, data.IndexOf(","));
data = data.Substring(data.IndexOf(",") + 1);
string v0 = data.Substring(0, data.IndexOf(","));
data = data.Substring(data.IndexOf(",") + 1);
string i = data;

double batteryVoltage = Convert.ToDouble(bv, CultureInfo.InvariantCulture);
double V0 = Convert.ToDouble(v0, CultureInfo.InvariantCulture);
double I = Convert.ToDouble(i, CultureInfo.InvariantCulture);

Comments

[Sayse]

You've abused Substring quite a lot here, what is wrong with string.Split(',') and TryParse?

[Sergey Berezovskiy]

This code works with your sample data. Please, give data which causes error

[S_F]

Since some people aren't aware of this - the sample data fails on certain regional settings, e.g. Polish uses "," as a decimal point and doesn't consider "4.5" a proper string to convert.

[Sergey Berezovskiy]

@user2790895 can you give us value of data when you get exception?

[Sergey Berezovskiy]

It should be a comment to question, not an answer to the reason of error

[Sayse]

and it will also probably fail on 0.02\r

[Sergey Berezovskiy]

Good notice on cutting off last character. That probably will be the reason of error

[S_F]

Right, fixed my answer as it does mess with the conversion. Still, CultureInfo setting should be there if the user has a regional setting which doesn't recognize "." as a decimal point.