IList<T>.Insert Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Inserts an item to the IList<T> at the specified index.

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


Sub Insert ( _
    index As Integer, _
    item As T _
void Insert(
    int index,
    T item


  • index
    Type: System.Int32
    The zero-based index at which item should be inserted.
  • item
    Type: T
    The object to insert into the IList<T>.


Exception Condition

index is not a valid index in the IList<T>.


The IList<T> is read-only.


If index equals the number of items in the IList<T>, then item is appended to the list.

In collections of contiguous elements, such as lists, the elements that follow the insertion point move down to accommodate the new element. If the collection is indexed, the indexes of the elements that are moved are also updated. This behavior does not apply to collections where elements are conceptually grouped into buckets, such as a hash table.

Version Information


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0


For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.