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

Reference

Definition

Namespace:: System.Collections.Generic

Assemblies:: mscorlib.dll, System.Collections.dll

Assemblies:: netstandard.dll, System.Collections.dll

Assembly:: System.Collections.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Source:: List.cs

Source:: List.cs

Source:: List.cs

Important

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Determines the index of a specific item in the IList.

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

int IList.IndexOf(object item);

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

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

Parameters

item: Object

The object to locate in the IList.

Returns

Int32

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

Implements

IndexOf(Object)

Exceptions

ArgumentException

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

Remarks

This method determines equality using the default equality comparer EqualityComparer<T>.Default for T, the type of values in the list.

This method performs a linear search; therefore, 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, 1.6, 2.0, 2.1
UWP	10.0

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