C# Bitwise left shift and set bit

Learned something new during leetcode.

In the past when I need to set a bit of a number to 1, I do the below reflexively:

// for example if I need to set the 10th bits of a 32 bits number to 1
// assuming the value is 0
result += (int)Math.Pow(2, 32-22);

But actually we can do it in following way:

result |= (1 << 9);

Explanation:

  1. First we do a right shift 9 times for 1:
  • Before (0000 0000 0000 0000 0000 0000 0000 0001)
  • After (0000 0000 0000 0000 0000 0010 0000 0000)
  1. Use bitwise OR assignment operator |=:
  • Such that the 10th bit of result must set to 1
#c#