C# | Array.BinarySearch(Array, Int32, Int32, Object, IComparer) Method (original) (raw)

Last Updated : 24 Jan, 2019

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:

public static int BinarySearch(Array arr, int index, int length, Object value, IComparer comparer)

Parameters:

Return Value: It returns the index of the specified value in the specified array if the value is found otherwise it returns a negative number. There are different cases of return values as follows:

Below programs illustrate the use of the above-discussed method:Example 1: In this example the array stores some string value and find some string value after sorting the array.

csharp `

// 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:

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

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.

csharp `

//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:

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

Reference:

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