Array.BinarySearch(Array, Object) Method with examples in C# (original) (raw)

Last Updated : 14 Apr, 2022

This method is used to search a specific element in the entire one-dimensional sorted array by using the IComparable interface which is implemented by each element of the array and by the specified object. Syntax:

public static int BinarySearch (Array array, object value);

Parameters:

array: It is the sorted 1-D array to search. value: It is the object to search for.

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:

Exceptions:

Below programs illustrate the above-discussed method: Example 1:

csharp `

// C# program to illustrate the // Array.BinarySearch(Array, Object) // Method using System;

class GFG {

// Main Method
public static void Main(String[] args) {
    

// taking an 1-D Array
int[] arr = new int[7] {1,5,7,4,6,2,3};

// for this method array
// must be sorted
Array.Sort(arr);

Console.Write("The elements of Sorted Array: ");

// calling the method to
// print the values
display(arr);

// taking the element which is 
// to search for in a variable
// It is not present in the array
object s = 8;


// calling the method containing
// BinarySearch method
result(arr, s);

// taking the element which is 
// to search for in a variable
// It is present in the array
object s1 = 4;


// calling the method containing
// BinarySearch method
result(arr, s1);

}

// containing BinarySearch Method static void result(int[] arr2, object k) {

// using the method
int res = Array.BinarySearch(arr2, k);

if (res < 0)
{
    Console.WriteLine("\nThe element to search for "+
                        "({0}) is not found.", k);
}

else
{
    Console.WriteLine("The element to search for "+
                "({0}) is at index {1}.", k, res);
}

}

// display method static void display(int[] arr1) {

// Displaying Elements of array 
foreach(int i in arr1) 
    Console.Write(i + " ");

}

}

`

Output:

The elements of Sorted Array: 1 2 3 4 5 6 7 The element to search for (8) is not found. The element to search for (4) is at index 3.

Example 2:

csharp `

// C# program to illustrate the // Array.BinarySearch(Array, Object) // Method using System;

class GFG {

// Main Method
public static void Main(String[] args) {
    

// taking an 1-D Array
int[] arr = new int[7] {1,5,7,4,6,2,3};

// for this method array
// must be sorted
Array.Sort(arr);

Console.Write("The elements of Sorted Array: ");

// calling the method to
// print the values
display(arr);

// it will return a negative value as 
// 9 is not present in the array
Console.WriteLine("\nIndex of 9 is: "+ 
           Array.BinarySearch(arr,8));

}

// display method static void display(int[] arr1) {

// Displaying Elements of array 
foreach(int i in arr1) 
    Console.Write(i + " ");

}

}

`

Output:

The elements of Sorted Array: 1 2 3 4 5 6 7 Index of 9 is: -8

Important Points:

Reference:

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