Свойство DataTypeInfoEnumerator.Current
Gets the current element in the collection.
Пространство имен: Microsoft.SqlServer.Dts.Runtime
Сборка: Microsoft.SqlServer.ManagedDTS (в Microsoft.SqlServer.ManagedDTS.dll)
Синтаксис
'Декларация
Public ReadOnly Property Current As Object
Get
'Применение
Dim instance As DataTypeInfoEnumerator
Dim value As Object
value = instance.Current
public Object Current { get; }
public:
virtual property Object^ Current {
Object^ get () sealed;
}
abstract Current : Object
override Current : Object
final function get Current () : Object
Значение свойства
Тип: System.Object
The current element in the collection.
Реализует
Замечания
After an enumerator is created, or after a call to the Reset method, the MoveNext method must be called to advance the enumerator to the first element of the collection before reading the value of the Current property; otherwise, Current is undefined and throws an exception.
Current also throws an exception if the last call to MoveNext returned false, which indicates the end of the collection.
Current does not move the position of the enumerator, and consecutive calls to the Current return the same object until either MoveNext or Reset is called.
An enumerator remains valid as long as the collection remains unchanged. If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is invalidated and becomes irrecoverable. If the collection is modified between calls to MoveNext and Current, Current returns the element that it is set to, even if the enumerator has been invalidated.
Примеры
The following code sample creates an enumerator, and then uses the Current, MoveNext, and Reset methods to navigate over the collection.
using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.SqlServer.Dts.Runtime;
namespace DataTypeInfos_GetEnum_Current
{
class Program
{
static void Main(string[] args)
{
//Create the DataTypeInfos collection.
DataTypeInfos dataInfos = new Application().DataTypeInfos;
//Create the Enumerator.
DataTypeInfoEnumerator myEnumerator = dataInfos.GetEnumerator();
Console.WriteLine("The collection contains the following values:");
int i = 0;
DataTypeInfo dtiObject;
while ((myEnumerator.MoveNext()) && (myEnumerator.Current != null))
{
dtiObject = (DataTypeInfo)myEnumerator.Current;
Console.WriteLine("[{0}] {1} {2}", i++, dtiObject.TypeName, dtiObject.TypeEnumName);
}
// Reset puts the index pointer before the beginning.
// Do not retrieve from the collection until MoveNext is called.
myEnumerator.Reset();
myEnumerator.MoveNext();
// Now that the enumerator has been reset, and moved to the
// first item in the collection, show the first item.
dtiObject = (DataTypeInfo)myEnumerator.Current;
Console.WriteLine("The first item in the enumerator after Reset:");
Console.WriteLine("{0}, {1}", dtiObject.TypeName, dtiObject.TypeEnumName);
}
}
}
Imports System
Imports System.Collections.Generic
Imports System.Text
Imports Microsoft.SqlServer.Dts.Runtime
Namespace DataTypeInfos_GetEnum_Current
Class Program
Shared Sub Main(ByVal args() As String)
'Create the DataTypeInfos collection.
Dim dataInfos As DataTypeInfos = New Application().DataTypeInfos
'Create the Enumerator.
Dim myEnumerator As DataTypeInfoEnumerator = dataInfos.GetEnumerator()
Console.WriteLine("The collection contains the following values:")
Dim i As Integer = 0
Dim dtiObject As DataTypeInfo
While (myEnumerator.MoveNext()) &&(myEnumerator.Current <> Nothing)
dtiObject = CType(myEnumerator.Current, DataTypeInfo)
Console.WriteLine("[{0}] {1} {2}",i = Console.WriteLine("[{0}] {1} {2}",i + 1
End While
' Reset puts the index pointer before the beginning.
' Do not retrieve from the collection until MoveNext is called.
myEnumerator.Reset()
myEnumerator.MoveNext()
' Now that the enumerator has been reset, and moved to the
' first item in the collection, show the first item.
dtiObject = CType(myEnumerator.Current, DataTypeInfo)
Console.WriteLine("The first item in the enumerator after Reset:")
Console.WriteLine("{0}, {1}", dtiObject.TypeName, dtiObject.TypeEnumName)
End Sub
End Class
End Namespace
Sample Output:
The collection contains the following values:
[0] float DT_R4
[1] double-precision float DT_R8
[2] currency DT_CY
[3] date DT_DATE
[4] Boolean DT_BOOL
[5] decimal DT_DECIMAL
[6] single-byte signed integer DT_I1
[7] single-byte unsigned integer DT_UI1
[8] two-byte signed integer DT_I2
[9] two-byte unsigned integer DT_UI2
[10] four-byte signed integer DT_I4
[11] four-byte unsigned integer DT_UI4
[12] eight-byte signed integer DT_I8
[13] eight-byte unsigned integer DT_UI8
[14] file timestamp DT_FILETIME
[15] unique identifier DT_GUID
[16] byte stream DT_BYTES
[17] string DT_STR
[18] Unicode string DT_WSTR
[19] numeric DT_NUMERIC
[20] database date DT_DBDATE
[21] database time DT_DBTIME
[22] database timestamp DT_DBTIMESTAMP
[23] image DT_IMAGE
[24] text stream DT_TEXT
[25] Unicode text stream DT_NTEXT
The first item in the enumerator after Reset:
float, DT_R4