Question

I found this code to reverse a string using the or operator,

public static string ReverseXor(string s)
{

      if (s == null) return null; 
      char[] charArray = s.ToCharArray(); 
      int len = s.Length - 1;

      for (int i = 0; i < len; i++, len--)
      { 
            charArray[i] ^= charArray[len]; 
            charArray[len] ^= charArray[i]; 
            charArray[i] ^= charArray[len]; }

       //some more code
}

The problem is I’m not understand in what’s happening inside the for loop, can someone explain this to me?

Thank you.

Answer 1

Here’s how you can swap two values A, B without a temporary intermediate variable:

A = A Xor B
B = A Xor B
A = A Xor B

Ref: XOR swap algorithm

Here’s a 8 bit example:

A = 10010010
B = 01111001

A = A Xor B = 11101011
B = A Xor B = 10010010
A = A Xor B = 01111001