Array.BinarySearch Method (Array, Int32, Int32, Object, IComparer)

Syntax

'Declaration
<SecuritySafeCriticalAttribute> _
Public Shared Function BinarySearch ( _
    array As Array, _
    index As Integer, _
    length As Integer, _
    value As Object, _
    comparer As IComparer _
) As Integer

[SecuritySafeCriticalAttribute]
public static int BinarySearch(
    Array array,
    int index,
    int length,
    Object value,
    IComparer comparer
)

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.

The comparer customizes how the elements are compared.

If comparer is not nulla null reference (Nothing in Visual Basic), the elements of array are compared to the specified value using the specified IComparer implementation. The elements of array must already be sorted in increasing value according to the sort order defined by comparer; otherwise, the result might be incorrect.

If comparer is nulla null reference (Nothing in Visual Basic), the comparison is done using the IComparable implementation provided by the element itself or by the specified value. The elements of array must already be sorted in increasing value according to the sort order defined by the IComparable implementation; otherwise, the result might be incorrect.

Note:
If comparer is nulla null reference (Nothing in Visual Basic) and value does not implement the IComparable interface, the elements of array are not tested for IComparable before the search begins. An exception is thrown if the search encounters an element that does not implement IComparable.

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 using IComparable. 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 implementation, even if value is nulla null reference (Nothing in Visual Basic). That is, the IComparable 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