While using listbox in c#, how can learn the count of selecteditems?
Listbox items: A,B,C,D. For example, I select C and D.
I want to make a loop in order to assign selecteditems.
How can I achieve it? How can I learn the number of selected item?
Thank you
Maybe you are looking for this listbox1.GetSelectedIndices().Count();
Use the following code:
This return integer:
listBox.SelectedItems.Count
this will return the number as string :
listBox.SelectedItems.Count.ToString()
You ought to be able to achieve this using something like so:
var count = (from item in listBox.Items where item.Selected select item).Count();
The above is a way to get this using Linq (so you will need a reference to System.Linq) but could easily be expanded to use a more primitive means such as a loop.
int count = 0;
foreach(ListItem item in this.ListBox1.Items)
{
if(item.Selected)
{
count++;
}
}
int c = count;
Related
I am populating a listBox at runtime from a database as follows:
List<FILE_REPORT_TYPES> ReportTypes = GetReportTypesFromDatabase(ReportMappingIds)
BindingList<FILE_REPORT_TYPES> pbReportTypesBindingList = new BindingList<FILE_REPORT_TYPES>(ReportTypes);
listBoxReports.DataSource = ReportTypesBindingList;
listBoxReports.DisplayMember = "REPORT_DESCRIPTION";
listBoxReports.ValueMember = "REPORT_ID";
I then would like select multiple items on the listBox when running the windows form and retrieve each individual Value of my selections. If only one selection is made one could do the following:
listBoxReports.SelectedValue;
I would like to do the following:
var list = listBoxReports.SelectedValues;
However this is not allowed i.e. "SelectedValues" does not exist.
Some people are erroneously suggesting that in this particular case SelectedIndices may be used. It cannot be used, I am trying to retrieve the "VALUE". This cannot be done (in this particular case):
listBox.Items[i].Value;
I think the solution should be along the lines of:
foreach(var line in listBox.Items)
{
var res= ((SOME CASTING)line).Value;
}
To get the selected items you have 2 options
a.) ListBox.SelectedIndices which returns the indices of the selected items which you then need to use to look up in the Items property what the value is or
b.) ListBox.SelectedItems which returns you a collection with the selected items themselves (be aware that it is an objectlist so you need to transform the items into your appropriate datatype).
Edit: With the additional information the following is possible
List<FILE_REPORT_TYPES> mySelectedList = new List<FILE_REPORT_TYPES>();
foreach (Object selectedItem in ListBox.SelectedItems)
{
mySelectedList.Add( ((FILE_REPORT_TYPES)selectedItem) );
}
You can use ListBox.SelectedIndices or ListBox.SelectedItems.
If you want to get all selected-items, you can let the foreach cast:
foreach(FILE_REPORT_TYPES frt in listBox.SelectedItems)
{
// ...
}
or if you want to get the ReportID into a list with the help of LINQ:
List<decimal> reportIds = listBox.SelectedItems.Cast<FILE_REPORT_TYPES>()
.Select(frt => frt.REPORT_ID)
.ToList();
Alternative to the selected value you could do the following
listBoxReports.SelectedItems;
Answer (the casting is the trick):
List<decimal> reportIds = new List<decimal>();
foreach(var line in listBoxReports.SelectedItems)
{
reportIds.Add(((PB_FILE_REPORT_TYPES)line).REPORT_ID);
}
You may try like below
List<FILE_REPORT_TYPES> reportList = new List<FILE_REPORT_TYPES>();
foreach(var item in listBox.SelectedItems)
{
reportList.Add((FILE_REPORT_TYPES)item);
}
I am having trouble with removing an item from a list in c#. My current code is below:
for (int i = current.Count - 1; i >= 0; i--)
{
foreach (ListItem li in sp_list.Items)
{
if (li.Text == current[i].uname)
{
current.RemoveAt(i);
}
}
}
The aim of the code is to compare the existing items in a list box with newly added items so I know which items have just been added. So currently I am getting the current list box items from the database (they are stored here, it is a databound list box), entering these into a list and for each of the list items, comparing them with the items in a list box and if they match, remove the item from the list.
Therefore, in the end, if I add two new entries, the list should only be storing the two newly added values.
The code does not work as the first item is removed fine, but then, the value of i is greater than current.count - and therefore I get an out of range exception!
Could someone help me with this issue? Apologies about the confusing question, it's hard to explain! Thanks
You can do it with Linq. Not sure if casting to ListItem needed (you can remove it)
current.RemoveAll(x => sp_list.Items.Cast<ListItem>()
.Any(li => li.Text == x.uname));
Once you've found the matching value, and removed it from the list, you want to break out of the inner loop to check the next item.
if (li.Text == current[i].uname)
{
current.RemoveAt(i);
break;
}
Your nesting is wrong, I think you wanted,
foreach (ListItem li in sp_list.Items)
{
for (int i = current.Count - 1; i >= 0; i--)
{
if (li.Text == current[i].uname)
{
current.RemoveAt(i);
}
}
}
alternatively, use linq,
// For lookup performance.
var items = new HashSet(sp_list.Items.Select(i => i.text));
current = current.Where(c => !items.Contains(c.uname)).ToList();
How about this:
foreach (ListItem li in sp_list.Items) {
if (current.Contains(li.Text)) {
current.Remove(li.Text);
}
}
Put a break statement after the RemoveAt so you don't remove that item again.
you can travel the list in reverse order and remove items using RemoveAt(i).
also for efficiency purposes you may want to put the ListItem texts in a Set so you can don't have to loop though the sp_list.Items for each of your current items.
I have a CheckedListBox bound to a DataTable. Now I need to check some items programmatically, but I find that the SetItemChecked(...) method only accepts the item index.
Is there a practical way to get an item by text/label, without knowing the item index?
(NOTE: I've got limited experience with WinForms...)
You can implement your own SetItemChecked(string item);
private void SetItemChecked(string item)
{
int index = GetItemIndex(item);
if (index < 0) return;
myCheckedListBox.SetItemChecked(index, true);
}
private int GetItemIndex(string item)
{
int index = 0;
foreach (object o in myCheckedListBox.Items)
{
if (item == o.ToString())
{
return index;
}
index++;
}
return -1;
}
The checkListBox uses object.ToString() to show items in the list. You you can implement a method that search across all objects.ToString() to get an item index. Once you have the item index, you can call SetItemChecked(int, bool);
Hope it helps.
You may try to browse your Datatable. YOu can do a foreach on the DataTabke.Rows property or use SQL syntax as below:
DataTable dtTable = ...
DataRow[] drMatchingItems = dtTable.Select("label = 'plop' OR label like '%ploup%'"); // I assumed there is a "label" column in your table
int itemPos = drMatchingItems[0][id]; // take first item, TODO: do some checking of the length/matching rows
Cheers,
I am answering it very late, I hope it will help someone. If you want to find any item by name we can do it in two steps. First get index of item by text and then we can get actual item with the help of index.
var selectedItemIndex = cbxList.Items.IndexOf("sometext");
var selectedItem = cbxList.Items[selectedItemIndex];
I would like to display text that is stored in my list.
I have the index number, and would like to use the index number to get the item from the collection.
Thx
If it's a List<string>, why not just use:
string item = list[index];
?
You can use ElementAt:
var item = list.ElementAt(3);
Or simply use the indexer, like:
var item = list[3];
I have this code:
foreach (var item in ListView1.Items)
{
ListView1.Items.Remove(item);
ListView21.Items.Add(item);
}
the loop stops at half of the items?
Any idea?
EDIT
Well, maybe it's my mistake, I need to clarify that this is UltraListView control from Infrajistics, where I can't add item to another list unless I remove it or clone it from the original list.
But thanks, most of the comments regarding do not modify the list within the loop were correct, so this code works:
foreach (var item in listView1.Items)
{
var i = item.Clone(true);
listView2.Items.Add(i);
}
listView1.Items.Clear();
Thanks,
You cannot modify iterated collection, it should die with exception (or in undefined behavior).
Try making a copy of the array:
foreach (var item in ListView1.Items.ToArray())
{
ListView1.Items.Remove(item);
ListView21.Items.Add(item);
}
EDIT:
in fact, your example code can be achieved by writing:
ListView21.Items.AddRange(ListView1.Items);
ListView1.Items.Clear();
(which in fact isn't EXACTLY what you are doing, but gives the same result and I think it won't bother you having the same content in both listviews for a moment). The latter is supported since .NET2.0, first solution requires linq, and therefore .NET3.5.
You are modifying the collection you are looping through. Try using a for statement from top to bottom (from the item with the highest index to 0).
for (int i = ListView1.Items.Count - 1; i >= 0; i--)
{
var item = ListView1.Items[i];
ListView1.Items.Remove(item);
ListView21.Items.Insert(0, item);
}
It will cause a runtime exception, complaining that you cannot modify the collection while iterating through it. You have to use for loop instead.
for(int index = Items.Count; index > 0; index--)
{
.......
// use Add and RemoveAt
}
EDIT : As mentioned by others. If you just need to move items from one collection to the other. AddRange and Clear will be better.
Do you get any exception or error message? Looping in a collection and remove items from the same collection is always a bad idea.
This looks like the WinForms list view control, so:
ListViewItem[] items = ListView1.Items.ToArray();
ListView1.Items.Clear();
ListView21.Items.AddRange(items);
Why just not CopyTo() to new list and then Clear() items?
You are looping through all items, removing all of them, then adding them to another list. As others have commented, you cannot remove items from a list in a for-each. Why not looping through all items to add them to your other list, and then remove them all in one go?
foreach (var item in ListView1.Items)
{
ListView21.Items.Add(item);
}
ListView1.Items.Clear(); // remove all
PS: is this an ASP.NET listview or a WinForms listview?
That's because you're changing the collection inside the loop.
Use a normal for loop as follows:
for(int i=0; i < ListView1.Items.Count-1; i++)
{
ListView21.Items.Add(ListView1.Items[i]);
ListView1.Items.RemoveAt(i);
}