Insert Method

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Inserts an element into the ArrayList at the specified index.

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

public virtual void Insert(
	int index,
	Object value


Type: System..::..Int32
The zero-based index at which value should be inserted.
Type: System..::..Object
The Object to insert. The value can be nullNothingnullptrunita null reference (Nothing in Visual Basic).


IList..::..Insert(Int32, Object)

ArrayList accepts nullNothingnullptrunita null reference (Nothing in Visual Basic) as a valid value and allows duplicate elements.

If Count already equals Capacity, the capacity of the ArrayList is increased by automatically reallocating the internal array, and the existing elements are copied to the new array before the new element is added.

If index is equal to Count, value is added to the end of ArrayList.

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.

This method is an O(n) operation, where n is Count.