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GenericExtensionsBinarySearchT, TKey Method (IListT, FuncT, TKey, TKey)

Searches the entire sorted IListT for an element and returns the zero-based index of the element.

If the key is not found, a negative number is returned, which can be intepreted as the bitwise complement of the interval of indices that the key is in between, i.e.

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list[interval-1] < key < list[interval]

This differs from the "ordinary" binary search in allowing a keySelectorcomparer that knows how to compare a class with its key. Example, if the list contains classes of type T having an id number and the class is sorted on that id, then the keySelector returns the id number for that class.

Namespace:  DHI.Mike1D.Generic
Assembly:  DHI.Mike1D.Generic (in DHI.Mike1D.Generic.dll) Version: 19.0.0.0 (11.1.1.1111)
Syntax
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public static int BinarySearch<T, TKey>(
	this IList<T> list,
	Func<T, TKey> keySelector,
	TKey key
)

Parameters

list
Type: System.Collections.GenericIListT
List to search in
keySelector
Type: SystemFuncT, TKey
A function to extract a key from an element.
key
Type: TKey
The key to locate. The value can be null for reference types.

Type Parameters

T
The type of the objects in the list
TKey
The type of the argument to look for

Return Value

Type: Int32
The zero-based index of item in the sorted IListT, if item is found; otherwise, a negative number that is the bitwise complement of the index of the next element that is larger than item or, if there is no larger element, the bitwise complement of Count.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IListT. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
See Also