索引数组超出范围异常

您似乎正在为具有的数组创建和分配内存

bookingupdate = new BookingUpdate[c];

但实际上并没有创建BookingUpdate的实例。当您尝试设置数组元素的属性时，没有实际的BookingUpdate要更新——只有一个占位符。

我建议将您的代码更改为以下内容：

...
bookingupdate = new BookingUpdate[count];  // allocates space for the number of BookingUpdates to be created
for (int c = 0; c < count; c++)
{
    bookingupdate[c] = new BookingUpdate(); // create a new instance of BookingUpdate and assign it the array     
    bookingupdate[c].bookingID = (long)rdr["ID"];
    ...

我希望这能有所帮助！

Imho i将简化您使用Linq:构建该数组的方法

BookingUpdate[] bookingupdate = dt.AsEnumerable()
    .Select(r => new BookingUpdate{
        bookingID = r.Field<long>("ID"),
        fullUserName = r.Field<string>("VERANSTALTER"),
        newStart = r.Field<DateTime>("Von"),
        newEnd = r.Field<DateTime>("Bis"), // here was another bug in your originalcode
        newSubject = r.Field<string>("THEMA"),
        newlocation = r.Field<string>("BEZEICHNUNG"),
        deleted = r.Field<string>("STORNO") != null
    })
    .ToArray();

这样，您就不会遇到数组越界的问题。

如果访问n-Elements数组中超出范围的第n个元素，则需要访问n-1个元素。

bookingupdate = new BookingUpdate[c];   // You create an array of 5 elements for example 
bookingupdate[c].bookingID = (long)rdr["ID"]; // Here you access the 5th elements but there are only 4

问题与数组的大小有关；

 for (int c = 0; c < count; c++)
 {
    bookingupdate = new BookingUpdate[c];
    bookingupdate[c].bookingID = (long)rdr["ID"];

在上一段代码中，您首先要创建一个大小为0的数组（bookingupdate）；那么您正试图插入一个项目。即使你设法跳过了第一个，它也会再次失败。只需将这些行更新为以下内容；

bookingupdate = new BookingUpdate[count];
for (int c = 0; c < count; c++)
     {        
        bookingupdate[c].bookingID = (long)rdr["ID"];

            for (int c = 0; c < count; c++)
            {
                bookingupdate = new BookingUpdate[c];

对于c为零的循环，错误出现在第一次迭代时。即，您正试图创建一个长度为零的数组bookingupdate=新的bookingupdate[0]

在调用数组之前，您已经初始化了数组，但没有初始化类本身。此外，您的初始化是错误的

count = dt.Rows.Count;
bookingupdate = new BookingUpdate[count];
for (int c = 0; c < count; c++)
{
    bu = new BookingUpdate();
    bu.bookingID = (long)rdr["ID"]; // <---- Error is here
    bu.fullUserName = rdr["VERANSTALTER"].ToString();
    bu.newStart = (DateTime)rdr["VON"];
    bu.newStart = (DateTime)rdr["BIS"];
    bu.newSubject = rdr["THEMA"].ToString();
    bu.newlocation = rdr["BEZEICHNUNG"].ToString();
    if (rdr["STORNO"].ToString() != null)
    {
        bu.deleted = true;
    }
    else
    {
        bu.deleted = false;
    }
    bookingupdate[c] = bu;
}

数组具有基于零的索引。

创建bookingupdate = new BookingUpdate[c];时，最后一个索引为c-1。

您无法访问BookingUpdate[c]，因为它不存在。

比方说c = 4，这意味着我们定义了一个有4个元素的数组，它们是什么；

BookingUpdate[0]
BookingUpdate[1]
BookingUpdate[2]
BookingUpdate[3]

则CCD_ 9将等于不存在这样的索引的CCD_。

来自MSDN页面；

数组为零索引：具有n元素的数组从0索引到n-1。

使用此代码

public BookingUpdate[] getBookingUpdates(string token)
{
String command = "SELECT b.ID,b.VERANSTALTER, rr.VON ,rr.BIS, b.THEMA, b.STORNO, ra.BEZEICHNUNG from BUCHUNG b JOIN RESERVIERUNGRAUM rr on rr.BUCHUNG_ID = b.ID JOIN RAUM ra on ra.ID = rr.RAUM_ID WHERE b.UPDATE_DATE BETWEEN DATEADD (DAY , -20 , getdate()) AND getdate() AND b.BOOKVERNR = 0";
BookingUpdate[] bookingupdate;
SqlConnection connection = new SqlConnection(GetConnectionString());
connection.Open();
try
{
    SqlCommand cmd = new SqlCommand(command, connection);
    SqlDataReader rdr = null;
    int count = 0;
    rdr = cmd.ExecuteReader();

        while (rdr.Read())
        {
            DataTable dt = new DataTable();
            dt.Load(rdr);
            count = dt.Rows.Count;
            bookingupdate = new BookingUpdate[count];
            for (int c = 0; c < count; c++)
            {
                bookingupdate[c].bookingID = (long)rdr["ID"]; // <---- Error is here
                bookingupdate[c].fullUserName = rdr["VERANSTALTER"].ToString();
                bookingupdate[c].newStart = (DateTime)rdr["VON"];
                bookingupdate[c].newStart = (DateTime)rdr["BIS"];
                bookingupdate[c].newSubject = rdr["THEMA"].ToString();
                bookingupdate[c].newlocation = rdr["BEZEICHNUNG"].ToString();
                if (rdr["STORNO"].ToString() != null)
                {
                    bookingupdate[c].deleted = true;
                }
                else
                {
                    bookingupdate[c].deleted = false;
                }
            }
        }
}
catch (Exception ex)
{
    log.Error(ex.Message + "'n'rStackTrace:'n'r" + ex.StackTrace);
}
finally
{
    connection.Close();
}
return bookingupdate;

}