Array::BinarySearch<T> Method (array<T>, Int32, Int32, T, IComparer<T>)
Assembly: mscorlib (in mscorlib.dll)
public: generic<typename T> static int BinarySearch( array<T>^ array, int index, int length, T value, IComparer<T>^ comparer )
The type of the elements of the array.
- Type: array<>
The sorted one-dimensional, zero-based Array to search.
- Type: System::Int32
The starting index of the range to search.
- Type: System::Int32
The length of the range to search.
The object to search for.
Return ValueType: System::Int32
The index of the specified value in the specified array, if value is found. If value is not found and value is less than one or more elements in array, a negative number which is the bitwise complement of the index of the first element that is larger than value. If value is not found and value is greater than any of the elements in array, a negative number which is the bitwise complement of (the index of the last element plus 1).
array is nullptr.
index is less than the lower bound of array.
length is less than zero.
index and length do not specify a valid range in array.
comparer is nullptr, and value is of a type that is not compatible with the elements of array.
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. For example, you can use a System.Collections::CaseInsensitiveComparer as the comparer to perform case-insensitive string searches.
If comparer is not nullptr, the elements of array are compared to the specified value using the specified IComparer<T> generic interface 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 nullptr, the comparison is done using the IComparable<T> generic interface 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<T> implementation; otherwise, the result might be incorrect.
If comparer is nullptr and 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.
nullptr can always be compared with any other reference type; therefore, comparisons with nullptr do not generate an exception when using IComparable<T>. When sorting, nullptr is considered to be less than any other object.
For every element tested, value is passed to the appropriate IComparable<T> implementation, even if value is nullptr. That is, the IComparable<T> implementation determines how a given element compares to nullptr.
This method is an O(log n) operation, where n is length.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.