What's the easiest way to convert latitude and longitude to double values

Question

I've got a CSV file containing latitude and longitude values, such as:

"25°36'55.57""E","45°39'12.52""N"

Anyone have a quick and simple piece of C# code to convert this to double values?

Thanks

Answer 1

If you mean C# code to do this:

result = 25 + (36 / 60) + (55.57 / 3600)

First you'll need to parse the expression with Regex or some other mechanism and split it into the individual parts. Then:

String hour = "25";
String minute = "36";
String second = "55.57";
Double result = (hour) + (minute) / 60 + (second) / 3600;

And of course a switch to flip sign depending on N/S or E/S. Wikipedia has a little on that:

For calculations, the West/East suffix is replaced by a negative sign in the western hemisphere. Confusingly, the convention of negative for East is also sometimes seen. The preferred convention -- that East be positive -- is consistent with a right-handed Cartesian coordinate system with the North Pole up. A specific longitude may then be combined with a specific latitude (usually positive in the northern hemisphere) to give a precise position on the Earth's surface. (http://en.wikipedia.org/wiki/Longitude)

Answer 2

Thanks for all the quick answers. Based on the answer by amdfan, I put this code together that does the job in C#.

/// <summary>The regular expression parser used to parse the lat/long</summary>
private static Regex Parser = new Regex("^(?<deg>[-+0-9]+)[^0-9]+(?<min>[0-9]+)[^0-9]+(?<sec>[0-9.,]+)[^0-9.,ENSW]+(?<pos>[ENSW]*)$");

/// <summary>Parses the lat lon value.</summary>
/// <param name="value">The value.</param>
/// <remarks>It must have at least 3 parts 'degrees' 'minutes' 'seconds'. If it 
/// has E/W and N/S this is used to change the sign.</remarks>
/// <returns></returns>
public static double ParseLatLonValue(string value)
{
    // If it starts and finishes with a quote, strip them off
    if (value.StartsWith("\"") && value.EndsWith("\""))
    {
        value = value.Substring(1, value.Length - 2).Replace("\"\"", "\"");
    }

    // Now parse using the regex parser
    Match match = Parser.Match(value);
    if (!match.Success)
    {
        throw new ArgumentException(string.Format(CultureInfo.CurrentUICulture, "Lat/long value of '{0}' is not recognised", value));
    }

    // Convert - adjust the sign if necessary
    double deg = double.Parse(match.Groups["deg"].Value);
    double min = double.Parse(match.Groups["min"].Value);
    double sec = double.Parse(match.Groups["sec"].Value);
    double result = deg + (min / 60) + (sec / 3600);
    if (match.Groups["pos"].Success)
    {
        char ch = match.Groups["pos"].Value[0];
        result = ((ch == 'S') || (ch == 'W')) ? -result : result;
    }
    return result;
}