Question

I’m trying to populate combobox from listbox elements.

this is code:

foreach(string elements in (Application.OpenForms[1] as Impostazioni).listBox1)
        {
            cbxValuta.Items.Add(elements);
        }

but I get this error from Visual Studio 2012:

Error 1 foreach statement cannot operate on variables of type
‘System.Windows.Forms.ListBox’ because ‘System.Windows.Forms.ListBox’
does not contain a public definition for ‘GetEnumerator’

I dont know how solve this error.

Answer 1

If you want iterate over ListBox elements you must use Items property.

Try this:

foreach(string elements in (Application.OpenForms[1] as Impostazioni).listBox1.Items)
{
    cbxValuta.Items.Add(elements);
}

Error:

But now I get this error: Index was out of range. Must be non-negative
and less than the size of the collection. Parameter name: index

First of all you must check if Application.OpenForms is not null and not empty.

So before foreach you must add following line of code:

If Application.OpenForms is list:

if(Application.OpenForms != null && Application.OpenForms.Count != 0)

If Application.OpenForms is array:

if(Application.OpenForms != null && Application.OpenForms.Length != 0)