в 16:40, 26 мая 2010

2010-05-26T16:40:30Z

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2010-05-26T12:53:52Z

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==Add value pair to Hashtable and get value back by key==

<source lang="vbnet">Imports System
Imports System.Collections
Class Test
Shared Sub Main()
Dim myTable As New Hashtable()
myTable.Item("A") = 1
myTable.Item("B") = 44
myTable.Item("C") = 43
myTable.Item("D") = 33
myTable.Item("E") = 39
Dim Country As String = "C"
Dim Code As Integer = myTable.Item(Country)
Console.WriteLine(Code)
End Sub
End Class</source>
<pre class=codeResult>43</pre>

==ContainsKey==

<source lang="vbnet">Imports System.Collections
public class Test
public Shared Sub Main
Dim myTable As New Hashtable
Dim objKey As Object
Dim objValue As Object
"Populate the hash table.
myTable.Add("H", 1)
myTable.Add("L", 2)
"Check before inserting another value.
If Not myTable.ContainsKey("A") Then
myTable.Add("A", 78)
End If
"Remove a value.
myTable.Remove("L")
"Display the hash table values.
Console.WriteLine("The hash table contains " & myTable.Count & " elements.")
For Each objKey In myTable.Keys
objValue = myTable.Item(objKey)
Console.WriteLine("ELEMENT KEY: " & objKey.ToString & vbCrLf & _
"ELEMENT VALUE: " & objValue.ToString)
Next objKey

End Sub
End class</source>
<pre class=codeResult>The hash table contains 2 elements.
ELEMENT KEY: A
ELEMENT VALUE: 78
ELEMENT KEY: H
ELEMENT VALUE: 1</pre>

==Find value and key in a Hashtable==

<source lang="vbnet">Imports System.Collections
Public Module Hasher
Dim Tablet As Hashtable = New Hashtable()
Sub Main()
AddToTable()
FindItem("AAA")
FindKey("BBB")
End Sub
Public Sub AddToTable()
Tablet.Add("333", "WWWW")
Tablet.Add("444", "AAA")
Tablet.Add("BBB", "I386")
End Sub
Public Sub FindItem(ByVal item As String)
If Tablet.ContainsValue(item) Then
Console.WriteLine("Found {0} in the hashtable.", item)
End If
End Sub
Public Sub FindKey(ByVal key As String)
If Tablet.ContainsKey(key) Then
Console.WriteLine("Found {0} in the list.", key)
End If
End Sub
End Module</source>
<pre class=codeResult>Found AAA in the hashtable.
Found BBB in the list.</pre>

==Get Enumerator from Hashtable==

<source lang="vbnet">Imports System.Collections
public class Test
public Shared Sub Main
Dim Hash As New Hashtable()
Hash.Add("5", "A")
Hash.Add("6", "B")
Hash.Add("7", "C")

Dim Enumerator As IDictionaryEnumerator = Hash.GetEnumerator

While (Enumerator.MoveNext())
Console.WriteLine(Enumerator.Key.ToString + "=" + Enumerator.Value.ToString)
End While

End Sub
End class</source>
<pre class=codeResult>5=A
6=B
7=C</pre>

==Retrieve all keys, sort and iterate==

<source lang="vbnet">Option Strict On
Imports System.Collections
Public Module modMain
Public Sub Main()
Dim airports As New Hashtable
airports.Add("S", "SSS")
airports.Add("X", "XXX")
airports.Add("D", "DDD")
airports.Add("R", "RRR")

Dim keys As ICollection = airports.Keys
Dim keysArray(airports.Count - 1) As String
keys.CopyTo(keysArray, 0)
Array.Sort(keysArray)
For Each key As String in KeysArray
Console.WriteLine("{0} is {1}", key, airports(key))
Next
End Sub
End Module</source>
<pre class=codeResult>D is DDD
R is RRR
S is SSS
X is XXX</pre>

==Retrieve all values, sort and iterate==

<source lang="vbnet">Option Strict On
Imports System.Collections
Public Module modMain
Public Sub Main()
Dim airports As New Hashtable
airports.Add("S", "SSS")
airports.Add("X", "XXX")
airports.Add("D", "DDD")
airports.Add("R", "RRR")

Dim values As ICollection = airports.Values
Dim valuesArray(airports.Count - 1) As String
values.CopyTo(valuesArray, 0)
Array.Sort(valuesArray)
Console.WriteLine()
For Each value As String in valuesArray
Console.WriteLine(value)
Next
End Sub
End Module</source>
<pre class=codeResult>DDD
RRR
SSS
XXX</pre>

==Retrieve single value from Hashtable by key==

<source lang="vbnet">Option Strict On
Imports System.Collections
Public Module modMain
Public Sub Main()
Dim airports As New Hashtable
airports.Add("JFK", "John F. Kennedy, New York")
airports.Add("LAX", "Los Angeles International, Los Angeles")
airports.Add("ORD", "O"Hare International, Chicago")
airports.Add("LHR", "Heathrow Airport, London")
Console.WriteLine(airports.Item("JFK"))
End Sub
End Module</source>
<pre class=codeResult>John F. Kennedy, New York</pre>

==Use For Each to loop through all keys in Hashtable==

<source lang="vbnet">Imports System.Collections
public class Test
public Shared Sub Main
Dim myTable As New Hashtable
Dim objKey As Object
Dim objValue As Object
"Populate the hash table.
myTable.Add("H", 1)
myTable.Add("L", 2)
"Check before inserting another value.
If Not myTable.ContainsKey("A") Then
myTable.Add("A", 78)
End If
"Remove a value.
myTable.Remove("L")
"Display the hash table values.
Console.WriteLine("The hash table contains " & myTable.Count & " elements.")
For Each objKey In myTable.Keys
objValue = myTable.Item(objKey)
Console.WriteLine("ELEMENT KEY: " & objKey.ToString & vbCrLf & _
"ELEMENT VALUE: " & objValue.ToString)
Next objKey

End Sub
End class</source>
<pre class=codeResult>The hash table contains 2 elements.
ELEMENT KEY: A
ELEMENT VALUE: 78
ELEMENT KEY: H
ELEMENT VALUE: 1</pre>

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VB.Net Tutorial/Collections/Hashtable - История изменений

в 16:40, 26 мая 2010

Admin: 1 версия