List<'T>.AsReadOnly Method ()


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Returns a read-only ReadOnlyCollection<'T> wrapper for the current collection.

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

member AsReadOnly : unit -> ReadOnlyCollection<'T>

Return Value

Type: System.Collections.ObjectModel.ReadOnlyCollection<'T>

An object that acts as a read-only wrapper around the current List<'T>.

To prevent any modifications to the List<'T> object, expose it only through this wrapper. A ReadOnlyCollection<'T> object does not expose methods that modify the collection. However, if changes are made to the underlying List<'T> object, the read-only collection reflects those changes.

This method is an O(1) operation.

The following example demonstrates the AsReadOnly method. A List<'T> of strings with a capacity of 4 is created, because the ultimate size of the list is known to be exactly 4. The list is populated with four strings, and the AsReadOnly method is used to get a read-only IList<'T> generic interface implementation that wraps the original list.

An element of the original list is set to "Coelophysis" using the Item property (the indexer in C#), and the contents of the read-only list are displayed again to demonstrate that it is just a wrapper for the original list.

No code example is currently available or this language may not be supported.

Universal Windows Platform
Available since 10
.NET Framework
Available since 2.0
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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