如何在C＃中的字符串变量中存储列表框值

Question

I want to store all listbox control values in a string with "," separated so that I can show it in the label. I'm using for loop but giving error

 for (int i = 0; i < ListBox2.Items.Count; i++){

        if (ListBox2.Items[i].Selected == true || ListBox2.Items.Count > 0){
            string projectnames += ListBox2.Items[i].ToString();
        }
  }

Answer 1

string projectnames = "";
bool firstValue = true;

for (int i = 0; i < ListBox2.Items.Count; i++)
            {

                if (ListBox2.Items[i].Selected == true || ListBox2.Items.Count > 0)
                {
                   if(!firstValue)
                   {
                      projectnames += ", " + ListBox2.Items[i].ToString();
                   }
                   else
                   {
                      projectnames += ListBox2.Items[i].ToString();
                      firstValue = false;
                   }

                }

            }

Answer 2

Instead of the loop i'd use LINQ + String.Join :

var selected = ListBox2.Items.Cast<ListItem>()
    .Where(li => li.Selected)
    .Select(li => li.ToString());
string projectnames = String.Join(",", selected);

On that way it's much better to read and you don't need to care about trailing commas.

Answer 3

This will generate a string of all selected items in the list.

string projectnames = "";
for (int i = 0; i < ListBox2.Items.Count; i++)
{

    if (ListBox2.Items[i].Selected)
    {
       projectnames += ListBox2.Items[i].ToString() + ", ";
    }

 }

Answer 4

The most succinct method I can think of is:

var label = string.Join(",", listBox2.Items.Cast<string>());

(This uses System.Linq)

Answer 5

Try this, will help you!

protected void btnSave_Click(object sender, EventArgs e)
    {
        string selectedItem=string.Empty;
        if (ListBox1.Items.Count > 0)
        {
            for (int i = 0; i < ListBox1.Items.Count; i++)
            {
                if (ListBox1.Items[i].Selected)
                {
                    selectedItem += ListBox1.Items[i].Text.ToString() + ", ";
                    //insert command
                }
            }
        }
    }