ReadOnlyCollection<T>.IndexOf Method

Searches for the specified object and returns the zero-based index of the first occurrence within the entire ReadOnlyCollection<T>.

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

public int IndexOf(
	T value
)

Parameters

value
Type: T

The object to locate in the List<T>. The value can be null for reference types.

Return Value

Type: System.Int32
The zero-based index of the first occurrence of item within the entire ReadOnlyCollection<T>, if found; otherwise, -1.

Implements

IList<T>.IndexOf(T)

The ReadOnlyCollection<T> is searched forward starting at the first element and ending at the last element.

This method determines equality using the default comparer EqualityComparer<T>.Default.

This method performs a linear search; therefore, this method is an O(n) operation, where n is Count.

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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