LINQ Cookbook, Recipe 5: Concatenating the selected strings from a CheckedListBox (Kit George)
Ingredients:
- Visual Studio 2008 (Beta2 or Higher)
Categories: LINQ-To-Objects, LINQ and WinForms
Instructions:
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Open Visual Studio 2008, and Click ‘File/New Project’. Create a new Windows Forms Application project
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From the toolbox, drag a CheckedListBox to the main form, and a button. Ensure the listbox is large enough to view multiple items
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DoubleClick the form to creat the load event. Add this code to the load event (this simply populates the CheckedListBox with entries)
CheckedListBox1.Items.AddRange( _
New String() {"Apple", "Orange", "Banana", _
"Avocado", "Tomato", "Tamarillo", _
"Kiwifruit", "Cherry"})
Create the click event for the button (in the code editors dropdowns, in the left drop down, select Button1) and add this code
MsgBox( _
Aggregate Box In CheckedListBox1.CheckedItems _
Into Concat())
Public Module AggregateModule
<Extension()> Public Function Concat(Of Type)( _
ByVal ie As IEnumerable(Of Type)) As String
Dim str As String = ""
For Each item In ie
If str <> "" Then str &= ","
str &= item.ToString()
Next
Return str
End Function
End Module
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Alternatively, change the code in the button to be the following and remove the function we created (this is less code, but if you're going to use this code a lot, then writing the Concat function is preferred)
MsgBox((From c In _
CheckedListBox1.CheckedItems).Aggregate( _
Function(ByVal x, ByVal y) x + "," + y))
