convert string degrees into decimal units

Question

Given a string "3°5'2''" I need to convert it to a decimal representation.

Answer 1

The first step, obviously, is to convert your string notation to degrees, minutes, and seconds. That's simple string-parsing, so I'll leave that as an exercise.

Let's say you're going to use a Tuple for this (http://msdn.microsoft.com/en-us/library/system.tuple.aspx).

public static double GetDegreesFromDMS(Tuple<double,double,double> dms)
{
    // First, calculate total seconds.
    double seconds = (dms.Item2 * 60) + dms.Item3;
    // This makes the fraction of a degree this number / 3600
    return dms.Item1 + (seconds / 3600);
}

To call this, you would construct a Tuple with the DMS values like so:

var dms = new Tuple<double, double, double>(3, 5, 2);
var degrees = GetDegreesFromDMS(dms);

Good luck.

Answer 2

For the math portion, I will use the answer from https://stackoverflow.com/a/3249890/1783619 You could of course write your own implementation. I would create my own "Degree" class that looks like this:

public class Degree
{
    int degrees;
    int minutes;
    int seconds;

    public static Degree Parse(string input)
    {
      //Implementation below
    }

    public decimal ToDecimal()
    {
       // From https://stackoverflow.com/a/3249890/1783619
       // Modified to use floating point division since my inputs are ints.
       //Decimal degrees = 
       //   whole number of degrees, 
       //   plus minutes divided by 60, 
       //   plus seconds divided by 3600

       return degrees + (minutes/60f) + (seconds/3600f);
    }
}

In the parse function, I would split the string based on the well known delimiters and assign the class members based on the split string. Note that this function isn't very safe for bad input as is:

public static Degree Parse(string input)
{
   Degree parsedDegree = new Degree();

   string[] seperatedStrings = input.Split(new char[] {'°', '\''});
   parsedDegree.degrees = seperatedStrings[0];
   parsedDegree.minutes = seperatedStrings[1];
   parsedDegree.seconds = seperatedStrings[2];

   return parsedDegree;
}

To use it:

Degree myDegree = Degree.Parse("3°5'2''");
Decimal myDecimal = myDegree.ToDecimal();