title: Unable to cast object of type class to type 'System.String'
body: <p>Class 1</p>
  
  <pre><code>public class KlasaBetonaaaa
       {
           public string Naziv { get; set; }
           public double _Fck { get; set; }
       }
  </code></pre>
  
  <p>Class 2</p>
  
  <pre><code> public static class Database
       {
           public static KlasaBetonaaaa[] GetAllKlasaBetona()
           {
               return new KlasaBetonaaaa[]
               {
                   new KlasaBetonaaaa
                   {
                       Naziv = "C12/15",
                       _Fck = 12.0
                   };
               }
           }
       }
  </code></pre>
  
  <p>Class 3</p>
  
  <pre><code>public partial class Form1 : Form
      {
  
          public Form1()
          {
              InitializeComponent();
              {
  
              var klaseBetona = Database.GetAllKlasaBetona();
  
              klasaBetonaComboBox.Items.AddRange(klaseBetona);
  
              }
  
  
  private void klasaBetona_SelectedIndexChanged(object sender, EventArgs e)
          {
              var selectedBeton = klasaBetonaComboBox.SelectedItem;
              CalculateSomething((string)selectedBeton);
          }
  
  
          private void CalculateSomething(string selectedBeton)
          {
              fck.Text = selectedBeton;
          }
      }
  </code></pre>
  
  <p>This string selectedBeton is what i tried before with only 1 name converting to string from collection.
  Now i created new classes (Manual database)as and array and i dont know how to link it so when i pick "C12/15" to get _Fck value 15.0 in a label.</p>