Array.BinarySearch Method
System.Array
Array.BinarySearch(array
,
value
, [comparer
])
Array.BinarySearch(array
,index
,length
,value
, [comparer
])
array
(required; any array)The one-dimensional array to be searched
value
(required in first overloaded function; any)The value to search for in array
index
(required in second overloaded version; Integer)The array element at which the search is to start
length
(required in second overloaded version; Integer)The number of array elements to be searched
comparer
(optional; IComparer
)A BCL or user-defined class implementing the
IComparer
interface that determines how two items
are compared for equality.
An Integer representing the zero-based ordinal position of the
element matching value
This method provides a quick way to search for a value in a sorted one-dimensional array, returning the smallest index whose element is that value. It uses a binary search algorithm, which tends to take log^{2}(n) comparisons to find an item in an array of length n. For example, if n = 100,000, the number of comparisons is on the order of 17.
To illustrate, if arr
is an array of names in
alphabetical order, then the code:
Array.BinarySearch(arr, "steve")
returns the smallest index with element “steve.” If no such element exists, BinarySearch returns the negative number whose bitwise complement is the index of the first element that is larger than “steve.”
The array must be a one-dimensional array sorted ...
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