3.14 Modify Bit At Given Position In Integer Number

/* We are given an integer number n, a bit value v (v=0 or 1) and a position p. Write a sequence of operators (a few lines of C# code) that modifies n to hold the value v at the position p from the binary representation of n while preserving all other bits in n. */

namespace _14.ModifyBitAtGivenPositionInIntegerNumber
{
    using System;

    public class ModifyBitAtGivenPositionInIntegerNumber
    {
        public static void Main(string[] args)
        {
            checked
            {
                Console.Write("Enter a whole non-negative number: ");
                uint num = uint.Parse(Console.ReadLine());
                int positionP;
                do
                {
                    Console.Write("Enter index for Bit position: ");
                }
                while (!int.TryParse(Console.ReadLine(), out positionP) || positionP < 0 || positionP > 31);

                int bitValueToModified;
                do
                {
                    Console.Write("Enter value of bit on position P, to modifying: ");
                }
                while (!int.TryParse(Console.ReadLine(), out bitValueToModified) || bitValueToModified < 0 || bitValueToModified > 1);

                // Checking on given position in number bit value:
                int startBitValue = (int)((long)num >> positionP) & 1;

                // Comparing founded bit value and given is equals or not. If bit values is equals, modifying is not necesary and given number is output result.
                uint resultNum = num;
                if (startBitValue != bitValueToModified)
                {
                    long bitMask;
                    if (startBitValue == 0)
                    {
                        // Modifying bit value on given position from 0 to 1:
                        bitMask = 1 << positionP;
                        resultNum = (uint)((long)num | bitMask);
                    }
                    else
                    {
                        // Modifying bit value on given position from 1 to 0:
                        bitMask = ~(1 << positionP);
                        resultNum = (uint)(num & bitMask);
                    }
                }

                Console.WriteLine("The number after modifying bit value is: {0} !", resultNum);
            }
        }
    }
}