foreach array keeps overwritten (beginner)

The next peace of code,

foreach (var trksegg in trk.Segs)
        { 
        double lon = Convert.ToDouble(trksegg.Longitude);
        double lat = Convert.ToDouble(trksegg.Latitude);
        double[,] lonlat = { { lon, lat } };

Looks like to keeps overw开发者_开发百科riting my lonlat array, so the array never gets bigger the [0,0] lon value and [0,1] lat value.

This probably is a beginners question(i'm beginner and cannot figure it out), but how can i fill the array with multiple valua's. Thank you in advance.

just put the array declaration outside the loop

double[,] lonlat = new double[trk.Segs.Length, 2];
for (int i=0; i<trk.Segs.Length; i++) {
    lonlat[i,0] = Convert.ToDouble(trk.Segs[i].Longitude);
    lonlat[i,1] = Convert.ToDouble(trk.Segs[i].Latitude);
}

there is also one little mistake: an array doesn't have an Add method, it supports only indexed access, so if you write

arr = { { lon, lat } }

in a loop, it will always reassign new array to your var, so it also makes no sense. in my example lon and lat are added via indexes

You have declared the array inside your foreach loop, so it will create a new one each iteration of the loop. You should declare it outside the loop and use it inside, then you'll get what you want.

So:

double[,] lonlat;

foreach(var trsksegg in trk.Segs)
{
    lonlat = { { lon, lat } };
}

The lonlat variable is local to your foreach loop: the array it contains gets recreated in each iteration.

Arrays in C# cannot be grown. You could preallocate the array, as @Mikant does, or you could accumulate the results in a List<T>, or you could use LINQ:

var lonlats = trk.Segs.Select(
    trksegg => new[] {
        Convert.ToDouble(trksegg.Longitude),
        Convert.ToDouble(trksegg.Latitude)
    }).ToArray();