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List(T).IndexOf Method (T, Int32)

Searches for the specified object and returns the zero-based index of the first occurrence within the range of elements in the List(T) that extends from the specified index to the last element.

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

member IndexOf : 
        item:'T * 
        index:int -> int 

Parameters

item
Type: T
The object to locate in the List(T). The value can be a null reference (Nothing in Visual Basic) for reference types.
index
Type: System.Int32
The zero-based starting index of the search. 0 (zero) is valid in an empty list.

Return Value

Type: System.Int32
The zero-based index of the first occurrence of item within the range of elements in the List(T) that extends from index to the last element, if found; otherwise, –1.

ExceptionCondition
ArgumentOutOfRangeException

index is outside the range of valid indexes for the List(T).

The List(T) is searched forward starting at index and ending at the last element.

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 the number of elements from index to the end of the List(T).

The following code example demonstrates all three overloads of the IndexOf method. A List(T) of strings is created, with one entry that appears twice, at index location 0 and index location 5. The IndexOf(T) method overload searches the list from the beginning, and finds the first occurrence of the string. The IndexOf(T, Int32) method overload is used to search the list beginning with index location 3 and continuing to the end of the list, and finds the second occurrence of the string. Finally, the IndexOf(T, Int32, Int32) method overload is used to search a range of two entries, beginning at index location two; it returns –1 because there are no instances of the search string in that range.

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

.NET Framework

Supported in: 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

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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