Array implements the Array.IsReadOnly property because it is required by the IList interface. An array that is read-only does not allow the addition, removal, or modification of elements after the array is created.

If you require a read-only collection, use a System.Collections class that implements the IList interface.

If you cast or convert an array to an IList interface object, the IList.IsReadOnly property returns false. However, if you cast or convert an array to a IList`1 interface, the IsReadOnly property returns true.

Retrieving the value of this property is an O(1) operation.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0, 4.0.0.0