The one-dimensional Array is searched forward starting at startIndex and ending at startIndex plus count minus 1, if count is greater than 0.

The elements are compared to the specified value using the object.Equals(object) 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 int.MinValue and value is not found, this method returns int.MaxValue, which is System.Int32.MinValue - 1.

Passing the Array.Length of the array as the startindex will result in a return value of -1, while values greater than Length will raise an ArgumentOutOfRangeException.

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

In the .NET Framework version 2.0, this method uses the object.Equals(object) and IComparable.CompareTo(object) 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 object.Equals(object) and IComparable.CompareTo(object) methods of the value object itself.