Array.IList.IndexOf Method

July 28, 2014

Searches for the specified object and returns the index of the first occurrence within the current one-dimensional instance.

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

int IList.IndexOf(
	Object value
)

Parameters

value
Type: System.Object
The object to locate in the current Array.

Return Value

Type: System.Int32
The index of the first occurrence of value within the entire Array, if found; otherwise, the lower bound of the Array minus 1.

Implements

IList.IndexOf(Object)

ExceptionCondition
RankException

The current Array is multidimensional.

The one-dimensional 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.

Since most arrays will have a lower bound of zero, this method would generally return –1 when value is not found. In the rare case that the lower bound of the array is equal to Int32.MinValue and value is not found, this method returns Int32.MaxValue, which is System.Int32.MinValue - 1.

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

In the .NET Framework version 2.0, this method uses the Equals and CompareTo methods of the Array to determine whether the Object specified by the value parameter exists. In the earlier versions of the .NET Framework, this determination was made by using the Equals and CompareTo methods of the valueObject itself.

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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