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Collection(Of T).Remove Method

.NET Framework 4.5

Removes the first occurrence of a specific object from the Collection(Of T).

Namespace: System.Collections.ObjectModel
Assembly: mscorlib (in mscorlib.dll)

'Declaration
Public Function Remove ( _
	item As T _
) As Boolean

Parameters

item: Type: T
The object to remove from the Collection(Of T). The value can be Nothing for reference types.

Return Value

Type: System.Boolean
true if item is successfully removed; otherwise, false. This method also returns false if item was not found in the original Collection(Of T).

Implements

ICollection(Of T).Remove(T)

Remarks

This method determines equality using the default equality comparer EqualityComparer(Of T).Default for T, the type of values in the list.

This method performs a linear search; therefore, the average execution time is proportional to Count. That is, this method is an O(n) operation, where n is Count.

Notes to Inheritors

Derived classes can override RemoveItem to change the behavior of this method.

Examples

The following code example demonstrates many of the properties and methods of Collection(Of T). The code example creates a collection of strings, uses the Add method to add several strings, displays the Count, and lists the strings. The example uses the IndexOf method to find the index of a string and the Contains method to determine whether a string is in the collection. The example inserts a string using the Insert method and retrieves and sets strings using the default Item property (the indexer in C#). The example removes strings by string identity using the Remove method and by index using the RemoveAt method. Finally, the Clear method is used to clear all strings from the collection.

C++

Imports System
Imports System.Collections.Generic
Imports System.Collections.ObjectModel

Public Class Demo

    Public Shared Sub Main() 

        Dim dinosaurs As New Collection(Of String)

        dinosaurs.Add("Psitticosaurus")
        dinosaurs.Add("Caudipteryx")
        dinosaurs.Add("Compsognathus")
        dinosaurs.Add("Muttaburrasaurus")

        Console.WriteLine("{0} dinosaurs:", dinosaurs.Count)
        Display(dinosaurs)

        Console.WriteLine(vbLf & "IndexOf(""Muttaburrasaurus""): {0}", _
            dinosaurs.IndexOf("Muttaburrasaurus"))

        Console.WriteLine(vbLf & "Contains(""Caudipteryx""): {0}", _
            dinosaurs.Contains("Caudipteryx"))

        Console.WriteLine(vbLf & "Insert(2, ""Nanotyrannus"")")
        dinosaurs.Insert(2, "Nanotyrannus")
        Display(dinosaurs)

        Console.WriteLine(vbLf & "dinosaurs(2): {0}", dinosaurs(2))

        Console.WriteLine(vbLf & "dinosaurs(2) = ""Microraptor""")
        dinosaurs(2) = "Microraptor"
        Display(dinosaurs)

        Console.WriteLine(vbLf & "Remove(""Microraptor"")")
        dinosaurs.Remove("Microraptor")
        Display(dinosaurs)

        Console.WriteLine(vbLf & "RemoveAt(0)")
        dinosaurs.RemoveAt(0)
        Display(dinosaurs)

        Console.WriteLine(vbLf & "dinosaurs.Clear()")
        dinosaurs.Clear()
        Console.WriteLine("Count: {0}", dinosaurs.Count)

    End Sub 

    Private Shared Sub Display(ByVal cs As Collection(Of String)) 
        Console.WriteLine()
        For Each item As String In cs
            Console.WriteLine(item)
        Next item
    End Sub 
End Class 

' This code example produces the following output: 
' 
'4 dinosaurs: 
' 
'Psitticosaurus 
'Caudipteryx 
'Compsognathus 
'Muttaburrasaurus 
' 
'IndexOf("Muttaburrasaurus"): 3 
' 
'Contains("Caudipteryx"): True 
' 
'Insert(2, "Nanotyrannus") 
' 
'Psitticosaurus 
'Caudipteryx 
'Nanotyrannus 
'Compsognathus 
'Muttaburrasaurus 
' 
'dinosaurs(2): Nanotyrannus 
' 
'dinosaurs(2) = "Microraptor" 
' 
'Psitticosaurus 
'Caudipteryx 
'Microraptor 
'Compsognathus 
'Muttaburrasaurus 
' 
'Remove("Microraptor") 
' 
'Psitticosaurus 
'Caudipteryx 
'Compsognathus 
'Muttaburrasaurus 
' 
'RemoveAt(0) 
' 
'Caudipteryx 
'Compsognathus 
'Muttaburrasaurus 
' 
'dinosaurs.Clear() 
'Count: 0

Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

Platforms

Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference

Collection(Of T) Class

System.Collections.ObjectModel Namespace

RemoveAt

Add

Insert

Other Resources

Performing Culture-Insensitive String Operations in Collections

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