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Delete last item from array

How to remove the last element from an array in VB.NET. I need to separate the street and the house number.

STREET

  • Divide the address into spaces
  • Delete last item (missing in code)
  • Attach array

NUMBER

  • Divide the address into spaces
  • get the last item

My code is:

'split address Dim addressArray() As String = args.Content.Split(" ") 'remove last element and return the joined array Return String.Join(" ", addressArray.Remove(addressArray.Length() - 1))
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4 answers
  Dim foo() As String = "This is a test".Split(New Char() {" "c}, StringSplitOptions.RemoveEmptyEntries) Array.Resize(foo, foo.Length - 1) Dim s As String = String.Join(" ", foo)

or use lists

  Dim foo As New List(Of String) foo.AddRange("This is a test".Split(New Char() {" "c}, StringSplitOptions.RemoveEmptyEntries)) foo.RemoveAt(foo.Count - 1) Dim s As String = String.Join(" ", foo)

Regarding LINQ usage and performance, judge for yourself

 Public Class Form1 'to LINQ or not to LINQ 'judge for yourself Dim stpw As New Stopwatch Private Sub Button1_Click(sender As System.Object, _ e As System.EventArgs) Handles Button1.Click Dim ipsumA() As String = New String() {"Lorem", "ipsum", "dolor", "sit", _ "amet", "consectetur", "adipisicing", _ "elit", "sed", "do", "eiusmod", _ "tempor", "incididunt", "ut", "labore", _ "et", "dolore", "magna", "aliqua", "Ut", _ "enim", "ad", "minim", "veniam", "quis", _ "nostrud", "exercitation", "ullamco", _ "laboris", "nisi", "ut", "aliquip", "ex", _ "ea", "commodo", "consequat", "Duis", "aute", _ "irure", "dolor", "in", "reprehenderit", "in", _ "voluptate", "velit", "esse", "cillum", "dolore", _ "eu", "fugiat", "nulla", "pariatur", "Excepteur", _ "sint", "occaecat", "cupidatat", "non", "proident", _ "sunt", "in", "culpa", "qui", "officia", "deserunt", _ "mollit", "anim", "id", "est", "laborum"} Const tries As Integer = 100000 Debug.WriteLine("") stpw.Reset() stpw.Start() For x As Integer = 1 To tries Dim s As String = arrayTake(ipsumA) Next stpw.Stop() Debug.WriteLine(stpw.ElapsedTicks.ToString) stpw.Reset() stpw.Start() For x As Integer = 1 To tries Dim s As String = arrayRsz(ipsumA) Next stpw.Stop() Debug.WriteLine(stpw.ElapsedTicks.ToString) End Sub Private Function arrayRsz(test As String()) As String Array.Resize(test, test.Length - 1) Return String.Join(" ", test) End Function Private Function arrayTake(test As String()) As String Return String.Join(" ", test.Take(test.Length - 1)) End Function End Class
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You cannot remove elements from an array. The size of the array is determined when it is created and cannot be changed.

You can create a result containing elements from an array, except for the last:

 Return String.Join(" ", addressArray.Take(addressArray.Length() - 1))

Edit:

If you are concerned about performance, you should not do Split or Join , but simply get parts of the string using simple string operations:

 Dim pos As Integer = args.Content.LastIndexOf(" "C) Dim street As String = args.Content.Substring(0, pos) Dim number As String = args.Content.Substring(pos + 1)

This is at least ten times faster than any other method presented here.

Edit 2:

Here is the performance test code (C #):

 Dim time As Performance = New Performance(1000000, 6) Dim address As String = "aölskdjf öawe öofij 42" Console.WriteLine(time.Take("SplitTakeJoin", Sub() Dim parts As String() = address.Split(" "c) Dim street As String = String.Join(" ", parts.Take(parts.Length - 1)) End Sub)) Console.WriteLine(time.Take("SplitResizeJoin", Sub() Dim parts As String() = address.Split(" "c) Array.Resize(parts, parts.Length - 1) Dim street As String = String.Join(" ", parts) End Sub)) Console.WriteLine(time.Take("Substring", Sub() Dim street As String = address.Substring(0, address.LastIndexOf(" "c)) End Sub))

Output:

 SplitTakeJoin 0,000511 ms. SplitResizeJoin 0,000323 ms. Substring 0,000031 ms.

using this performance testing class:

 Public Class Performance Private _iterations As Integer Private _displayDigits As Integer Private _emptyTime As TimeSpan Public Sub New(ByVal iterations As Integer, ByVal displayDigits As Integer) _iterations = iterations _displayDigits = displayDigits _emptyTime = TimeSpan.Zero _emptyTime = Take(Sub() End Sub) End Sub Private Function Take(ByVal action As Action) As TimeSpan Dim w As Stopwatch = Stopwatch.StartNew() For i As Integer = 0 To _iterations - 1 Step 10 Action() Action() Action() Action() Action() Action() Action() Action() Action() Action() Next w.Stop() Return w.Elapsed - _emptyTime End Function Public Function Take(ByVal title As String, ByVal action As Action) As String Dim Time As TimeSpan = Take(action) Return title + " " + (Time.TotalMilliseconds / Convert.ToDouble(_iterations)).ToString("N" + _displayDigits.ToString()) + " ms." End Function End Class
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You can also try using Redim Preserve . These statements carry over from Visual Basic 6.0 days, and are not considered the .NET way of doing things, but this is another option. There may be performance issues, although in accordance with this article .

 Redim Preserve addressArray(addressArray.Length - 1)

To remove the last element of an array, you need:

  Redim Preserve addressArray(addressArray.Length - 2)

since they are based on a zero value and the length is based on.

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This will return everything but the last word / number to String as an array of strings.

 Return args.content.Split(" ").Take((args.content.Split(" ").Count - 1)).ToArray()
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