Collection<T>.IList.IndexOf(Object) Method

Reference

Definition

Namespace:: System.Collections.ObjectModel

Assemblies:: mscorlib.dll, System.Runtime.dll

Assemblies:: netstandard.dll, System.Runtime.dll

Assembly:: System.Runtime.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Source:: Collection.cs

Source:: Collection.cs

Source:: Collection.cs

Important

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Determines the index of a specific item in the IList.

 virtual int System.Collections.IList.IndexOf(System::Object ^ value) = System::Collections::IList::IndexOf;

int IList.IndexOf(object value);

abstract member System.Collections.IList.IndexOf : obj -> int
override this.System.Collections.IList.IndexOf : obj -> int

Function IndexOf (value As Object) As Integer Implements IList.IndexOf

Parameters

value: Object

The Object to locate in the IList.

Returns

Int32

The index of value if found in the list; otherwise, -1.

Implements

IndexOf(Object)

Exceptions

ArgumentException

value is of a type that is not assignable to the IList.

Remarks

This method determines equality using the default comparer Comparer<T>.Default. Comparer<T>.Default checks whether type T implements System.IComparable<T> and uses that implementation, if available. If not, Comparer<T>.Default checks whether type T implements System.IComparable. If type T does not implement either interface, this method uses Object.Equals.

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

Applies to

Product	Versions
.NET	Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9, 10
.NET Framework	2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard	1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1
UWP	10.0

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