How can I delete an item from an array in VB.NET?

As Heinzi said, an array has a fixed size. In order to 'remove an item' or 'resize' it, you'll have to create a new array with the desired size and copy the items you need as appropriate.

Here's code to remove an item from an array:

<System.Runtime.CompilerServices.Extension()> _Function RemoveAt(Of T)(ByVal arr As T(), ByVal index As Integer) As T()    Dim uBound = arr.GetUpperBound(0)    Dim lBound = arr.GetLowerBound(0)    Dim arrLen = uBound - lBound    If index < lBound OrElse index > uBound Then        Throw New ArgumentOutOfRangeException( _        String.Format("Index must be from {0} to {1}.", lBound, uBound))    Else        'create an array 1 element less than the input array        Dim outArr(arrLen - 1) As T        'copy the first part of the input array        Array.Copy(arr, 0, outArr, 0, index)        'then copy the second part of the input array        Array.Copy(arr, index + 1, outArr, index, uBound - index)        Return outArr    End IfEnd Function

You can use it as such:

Module Module1    Sub Main()        Dim arr = New String() {"abc", "mno", "xyz"}        arr.RemoveAt(1)    End SubEnd Module

The code above removes the second element ("mno") [which has an index of 1] from the array.

You need to be developing in .NET 3.5 or higher in order to use the extension method.If you're using .NET 2.0 or 3.0, you can call the method as such

arr = RemoveAt(arr, 1)

I hope this is what you need.

Update

After running tests based on ToolMakerSteve's comment it appears the initial code does not modify the array you want to update because of the ByVal used in the function's declaration. However, writing code like arr = arr.RemoveAt(1) or arr = RemoveAt(arr, 1) does modify the array because it reassigns the modified array to the original.

Find below the updated method (subroutine) for removing an element from an array.

<System.Runtime.CompilerServices.Extension()> _Public Sub RemoveAt(Of T)(ByRef arr As T(), ByVal index As Integer)    Dim uBound = arr.GetUpperBound(0)    Dim lBound = arr.GetLowerBound(0)    Dim arrLen = uBound - lBound    If index < lBound OrElse index > uBound Then        Throw New ArgumentOutOfRangeException( _        String.Format("Index must be from {0} to {1}.", lBound, uBound))    Else        'create an array 1 element less than the input array        Dim outArr(arrLen - 1) As T        'copy the first part of the input array        Array.Copy(arr, 0, outArr, 0, index)        'then copy the second part of the input array        Array.Copy(arr, index + 1, outArr, index, uBound - index)        arr = outArr    End IfEnd Sub

Usage of the method is similar to the original, except there is no return value this time so trying to assign an array from the return value will not work because nothing is returned.

Dim arr = New String() {"abc", "mno", "xyz"}arr.RemoveAt(1)  ' Output: {"abc", "mno"} (works on .NET 3.5 and higher)RemoveAt(arr, 1) ' Output: {"abc", "mno"} (works on all versions of .NET fx)arr = arr.RemoveAt(1)  'will not work; no return valuearr = RemoveAt(arr, 1) 'will not work; no return value

Note:

1. I use a temporary array for the process because it makes my intentions clear and that is exactly what VB.NET does behind the scenes when you do Redim Preserve. If you would like to modify the array in-place using Redim Preserve, see ToolmakerSteve's answer.

2. The RemoveAt methods written here are extension methods. In order for them to work, you will have to paste them in a Module. Extension methods will not work in VB.NET if they are placed in a Class.

3. Important If you will be modifying your array with lots of 'removes', it is highly recommended to use a different data structure such as List(Of T) as suggested by other answerers to this question.

You can't. I would suggest that you put the array elements into a List, at least then you can remove items. An array can be extended, for example using ReDim but you cannot remove array elements once they have been created. You would have to rebuild the array from scratch to do that.

If you can avoid it, don't use arrays here, use a List.

One line using LINQ:

Dim arr() As String = {"uno", "dos", "tres", "cuatro", "cinco"}Dim indx As Integer = 2arr = arr.Where(Function(item, index) index <> indx).ToArray 'arr = {"uno", "dos", "cuatro", "cinco"}

Remove first element:

arr = arr.Skip(1).ToArray

Remove last element:

arr = arr.Take(arr.length - 1).ToArray