c# 2D array error: need Help!

Although you have instantiated an array of [700,700] MapTileData objects, you haven't instatiated the objects wit$$anonymous$$n that array, the following line

 worldMap = new MapTileData[700,700]

makes an array for the objects, but doesn't create the actual objects wit$$anonymous$$n it. To fill the array you have to iterate over all the objects and do somet$$anonymous$$ng along the lines of,

 for(int i=0; i<700; i++){
    for(int j=0; j<700; j++){
       worldMap[i,j] = new MapTileData();
    }
 }

So what you could have at the end is...

 public void SetWorldMapOutline()

{

 worldMap = new MapTileData[700, 700];
 for (int y = 0; y < 700; y++)
 {
     axisY = size - y;
     for (int x = 0; x < 700; x++)
     {


             worldMap[y, x] = new MapTileData();
             worldMap[y, x].X = 0;


     }
 }

}

or similar.