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IndexOf Method (Object)
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ArrayList.IndexOf Method (Object)

Searches for the specified Object and returns the zero-based index of the first occurrence within the entire ArrayList.

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

abstract IndexOf : 
        value:Object -> int  
override IndexOf : 
        value:Object -> int

Parameters

value
Type: System.Object

The Object to locate in the ArrayList. The value can be a null reference (Nothing in Visual Basic).

Return Value

Type: System.Int32
The zero-based index of the first occurrence of value within the entire ArrayList, if found; otherwise, -1.

Implements

IList.IndexOf(Object)

The ArrayList is searched forward starting at the first element and ending at the last element.

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

This method determines equality by calling Object.Equals.

Starting with the .NET Framework 2.0, this method uses the collection’s objects’ Equals and CompareTo methods on item to determine whether item exists. In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the item parameter on the objects in the collection.

The following code example shows how to determine the index of the first occurrence of a specified element.

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

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0
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