GetEnumerator 方法
下面的示例说明 GetEnumerator 方法的用法。包括在枚举数为活动的情况下从基础 DataTable 中删除行时枚举数的行为。
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public static void Main()
{
try
{
DataTable userTable = new DataTable("peopleTable");
userTable.Columns.Add("Id", typeof(int));
userTable.Columns.Add("Name", typeof(string));
// Note that even if you create the DataTableReader
// before adding the rows, the enumerator can still
// visit all the rows.
DataTableReader reader = userTable.CreateDataReader();
userTable.Rows.Add(new object[] { 1, "Peter" });
userTable.Rows.Add(new object[] { 2, "Mary" });
userTable.Rows.Add(new object[] { 3, "Andy" });
userTable.Rows.Add(new object[] { 4, "Russ" });
IEnumerator enumerator = reader.GetEnumerator();
// Keep track of whether the row to be deleted
// has actually been deleted yet. This allows
// this sample to demonstrate that the enumerator
// is able to survive row deletion.
bool isRowDeleted = false;
while (enumerator.MoveNext())
{
DbDataRecord dataRecord = (DbDataRecord)enumerator.Current;
// While the enumerator is active, delete a row.
// This doesn't affect the behavior of the enumerator.
if (!isRowDeleted)
{
isRowDeleted = true;
userTable.Rows[2].Delete();
}
Console.WriteLine(dataRecord.GetString(1));
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
Console.ReadLine();
view plaincopy to clipboardprint?
public static void Main()
{
try
{
DataTable userTable = new DataTable("peopleTable");
userTable.Columns.Add("Id", typeof(int));
userTable.Columns.Add("Name", typeof(string));
// Note that even if you create the DataTableReader
// before adding the rows, the enumerator can still
// visit all the rows.
DataTableReader reader = userTable.CreateDataReader();
userTable.Rows.Add(new object[] { 1, "Peter" });
userTable.Rows.Add(new object[] { 2, "Mary" });
userTable.Rows.Add(new object[] { 3, "Andy" });
userTable.Rows.Add(new object[] { 4, "Russ" });
IEnumerator enumerator = reader.GetEnumerator();
// Keep track of whether the row to be deleted
// has actually been deleted yet. This allows
// this sample to demonstrate that the enumerator
// is able to survive row deletion.
bool isRowDeleted = false;
while (enumerator.MoveNext())
{
DbDataRecord dataRecord = (DbDataRecord)enumerator.Current;
// While the enumerator is active, delete a row.
// This doesn't affect the behavior of the enumerator.
if (!isRowDeleted)
{
isRowDeleted = true;
userTable.Rows[2].Delete();
}
Console.WriteLine(dataRecord.GetString(1));
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
Console.ReadLine();