Array.IndexOf(T) Method (T[], T)

Searches for the specified object and returns the index of the first occurrence within the entire Array.

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

static member IndexOf : 
        array:'T[] * 
        value:'T -> int 

Type Parameters

T

The type of the elements of the array.

Parameters

array
Type: T[]
The one-dimensional, zero-based Array to search.
value
Type: T
The object to locate in array.

Return Value

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

ExceptionCondition
ArgumentNullException

array is a null reference (Nothing in Visual Basic).

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

The elements are compared to the specified value using the Object.Equals method. If the element type is a nonintrinsic (user-defined) type, the Equals implementation of that type is used.

This method is an O(n) operation, where n is the Length of array.

The following code example demonstrates all three generic overloads of the IndexOf method. An array of strings is created, with one entry that appears twice, at index location 0 and index location 5. The IndexOf(T)(T[], T) method overload searches the array from the beginning, and finds the first occurrence of the string. The IndexOf(T)(T[], T, Int32) method overload is used to search the array beginning with index location 3 and continuing to the end of the array, and finds the second occurrence of the string. Finally, the IndexOf(T)(T[], 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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