C# | Array.BinarySearch(Array, Int32, Int32, Object, IComparer) Method
Last Updated : 24 Jan, 2019
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This method searches for an element which is in a one-dimensional sorted array within a range of elements using a specified IComparer interface. Syntax:csharp csharp
public static int BinarySearch(Array arr, int index, int length, Object value, IComparer comparer)Parameters:
- arr : The sorted one-dimensional Array which is to be searched.
- index : The starting index of the range from which searching will start.
- length : The length of the range in which the search will happen.
- value : The object to search for.
- comparer : When comparing elements then use the IComparer implementation.
- If the value is not found and value is less than one or more elements in the array, the negative number returned is the bitwise complement of the index of the first element that is larger than value.
- If the value is not found and value is greater than all elements in the array, the negative number returned is the bitwise complement of (the index of the last element plus 1).
- If this method is called with a non-sorted array, the return value can be incorrect and a negative number could be returned, even if the value is present in the array.
// C# program to demonstrate the
// Array.BinarySearch(Array,
// Int32, Int32, Object,
// IComparer) Method
using System;
class GFG {
// Main Method
public static void Main()
{
// initializes a new Array
string[] arr = new string[5] {"ABCD",
"IJKL", "XYZ", "EFGH", "MNOP"};
Console.WriteLine("The original Array");
// calling "display" function
display(arr);
Console.WriteLine("\nsorted array");
// sorting the Array
Array.Sort(arr);
display(arr);
Console.WriteLine("\n1st call");
// search for object "EFGH"
object obj1 = "EFGH";
// call the "FindObj" function
FindObj(arr, obj1);
Console.WriteLine("\n2nd call");
object obj2 = "ABCD";
FindObj(arr, obj2);
}
// find object method
public static void FindObj(string[] Arr,
object Obj)
{
int index = Array.BinarySearch(Arr, 0, 3,
Obj, StringComparer.CurrentCulture);
if (index < 0)
{
Console.WriteLine("The object {0} is not "+
"found\nNext larger object is"+
" at index {1}", Obj, ~index);
}
else
{
Console.WriteLine("The object {0} is at"+
" index {1}", Obj, index);
}
}
// display method
public static void display(string[] arr)
{
foreach(string g in arr)
{
Console.WriteLine(g);
}
}
}
Output:
Example 2: In this example, here we use "CreateInstance()" method to create a typed array and stores some integer value and search some values after sort the array.The original Array ABCD IJKL XYZ EFGH MNOP sorted array ABCD EFGH IJKL MNOP XYZ 1st call The object EFGH is at index 1 2nd call The object ABCD is at index 0
//C# program to demonstrate the
// Array.BinarySearch(Array,
// Int32, Int32, Object,
// IComparer) Method
using System;
class GFG
{
// Main Method
public static void Main()
{
// initializes a new Array.
Array arr = Array.CreateInstance(typeof(Int32), 8);
// Array elements
arr.SetValue(20, 0);
arr.SetValue(10, 1);
arr.SetValue(30, 2);
arr.SetValue(40, 3);
arr.SetValue(50, 4);
arr.SetValue(80, 5);
arr.SetValue(70, 6);
arr.SetValue(60, 7);
Console.WriteLine("The original Array");
// calling "display" function
display(arr);
Console.WriteLine("\nsorted array");
// sorting the Array
Array.Sort(arr);
display(arr);
Console.WriteLine("\n1st call");
// search for object 10
object obj1 = 10;
// call the "FindObj" function
FindObj(arr, obj1);
Console.WriteLine("\n2nd call");
object obj2 = 60;
FindObj(arr, obj2);
}
// find object method
public static void FindObj(Array Arr,
object Obj)
{
int index = Array.BinarySearch(Arr, 1, 4,
Obj, StringComparer.CurrentCulture);
if (index < 0)
{
Console.WriteLine("The object {0} is not found\n"+
"Next larger object is at index {1}",
Obj, ~index );
}
else
{
Console.WriteLine("The object {0} is at "+
"index {1}", Obj, index );
}
}
// display method
public static void display(Array arr)
{
foreach (int g in arr)
{
Console.WriteLine(g);
}
}
}
Output:
Reference:The original Array 20 10 30 40 50 80 70 60 sorted array 10 20 30 40 50 60 70 80 1st call The object 10 is not found Next larger object is at index 1 2nd call The object 60 is not found Next larger object is at index 5
