Array.BinarySearch<T> Method (array<T[], Int32, Int32, T)

Syntax

'Declaration
Public Shared Function BinarySearch(Of T) ( _
    array As T(), _
    index As Integer, _
    length As Integer, _
    value As T _
) As Integer

public static int BinarySearch<T>(
    T[] array,
    int index,
    int length,
    T value
)

Exceptions

Remarks

If the Array does not contain the specified value, the method returns a negative integer. You can apply the bitwise complement operator (~) to the negative result (in Visual Basic, Xor the negative result with -1) to produce an index. If this index is greater than or equal to the size of the array, there are no elements larger than value in the array. Otherwise, it is the index of the first element that is larger than value.

Either value or every element of array must implement the IComparable<T> generic interface, which is used for comparisons. The elements of array must already be sorted in increasing value according to the sort order defined by the IComparable<T> implementation; otherwise, the result might be incorrect.

Note:
If value does not implement the IComparable<T> generic interface, the elements of array are not tested for IComparable<T> before the search begins. An exception is thrown if the search encounters an element that does not implement IComparable<T>.

Duplicate elements are allowed. If the Array contains more than one element equal to value, the method returns the index of only one of the occurrences, and not necessarily the first one.

nulla null reference (Nothing in Visual Basic) can always be compared with any other reference type; therefore, comparisons with nulla null reference (Nothing in Visual Basic) do not generate an exception. When sorting, nulla null reference (Nothing in Visual Basic) is considered to be less than any other object.

Note:
For every element tested, value is passed to the appropriate IComparable<T> implementation, even if value is nulla null reference (Nothing in Visual Basic). That is, the IComparable<T> implementation determines how a given element compares to nulla null reference (Nothing in Visual Basic).

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

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

See Also

Reference