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C# | Set the bit at a specific position in the BitArray to the specified value

Last Updated : 11 Jul, 2025
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The BitArray class manages a compact array of bit values, which are represented as Booleans, where true indicates that the bit is on i.e, 1 and false indicates the bit is off i.e, 0. This class is contained in System.Collections namespace. BitArray.Set(Int32, Boolean) method is used to set the bit at a specific position in the BitArray to the specified value. Properties:
  • The BitArray class is a collection class in which the capacity is always the same as the count.
  • Elements are added to a BitArray by increasing the Length property.
  • Elements are deleted by decreasing the Length property.
  • Elements in this collection can be accessed using an integer index. Indexes in this collection are zero-based.
Syntax: 
public void Set (int index, bool value);
Parameters:
index : The zero-based index of the bit to set. value : The Boolean value to assign to the bit.
Exception: This method will give ArgumentOutOfRangeException if the index is less than zero or the index is greater than or equal to the number of elements in the BitArray. Note: This method is an O(1) operation. Below programs illustrate the use of BitArray.Set(Int32, Boolean) Method: Example 1: CSHARP 
// C# code to set the bit at
// a specific position in the
// BitArray to the specified value
using System;
using System.Collections;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating a BitArray myBitArr
        // Initializing all the values to false
        BitArray myBitArr = new BitArray(5, false);

        // Printing the values in myBitArr
        // It should display all the bits as false
        Console.WriteLine("Initially the bits are as : ");

        PrintIndexAndValues(myBitArr);

        // Setting bit at index 3 to true
        myBitArr.Set(3, true);

        // Printing the values in myBitArr
        Console.WriteLine("Finally the bits are as : ");

        PrintIndexAndValues(myBitArr);
    }

    // Function to display bits
    public static void PrintIndexAndValues(IEnumerable myArr)
    {
        foreach(Object obj in myArr)
        {
            Console.WriteLine(obj);
        }
    }
}
Output: 
Initially the bits are as : 
False
False
False
False
False
Finally the bits are as : 
False
False
False
True
False
Example 2: CSHARP 
// C# code to set the bit at
// a specific position in the
// BitArray to the specified value
using System;
using System.Collections;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating a BitArray myBitArr
        BitArray myBitArr = new BitArray(5);

        // Initializing all the bits in myBitArr
        myBitArr[0] = false;
        myBitArr[1] = true;
        myBitArr[2] = true;
        myBitArr[3] = false;
        myBitArr[4] = true;

        // Printing the values in myBitArr
        Console.WriteLine("Initially the bits are as : ");

        PrintIndexAndValues(myBitArr);

        // Setting bit at index 2 to false
        myBitArr.Set(2, false);

        // Setting bit at index 3 to true
        myBitArr.Set(3, true);

        // Printing the values in myBitArr
        Console.WriteLine("Finally the bits are as : ");

        PrintIndexAndValues(myBitArr);
    }

    // Function to display bits
    public static void PrintIndexAndValues(IEnumerable myArr)
    {
        foreach(Object obj in myArr)
        {
            Console.WriteLine(obj);
        }
    }
}
Output: 
Initially the bits are as : 
False
True
True
False
True
Finally the bits are as : 
False
True
False
True
True
Reference:

S

Sahil_Bansall
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