Bitwise Operators

All of the logic gates we've been using (AND, XOR, OR, etc) are part of every programming languages as bitwise operators. You've probably seen them before - here they are in JavaScript:

• & is AND
• || is OR
• ^ is XOR

And so on. In this video we dive in head-first and answer a pretty common interview question:

Create a routine that adds two positive integers together without using mathematic operators.

I got asked this once and drew a complete blank as I had no idea and let the interviewer know that. They tried to offer me clues but I was beyond any kind of help, in a completely foreign land. I knew absolutely nothing about binary!

If this is you, buckle up cause here we go!

The Code

Here's the code we'll be cycling on for the video:

<span class="hljs-keyword">const</span> add =<span class="hljs-keyword">function</span>(<span class="hljs-params">x,y</span>) {
  <span class="hljs-comment">//iterate until there is no carry</span>
  <span class="hljs-keyword">let</span> should_carry = <span class="hljs-literal">null</span>;
  <span class="hljs-keyword">while</span>(should_carry !== <span class="hljs-number">0</span>){
    should_carry = x &amp; y;
    x = x ^ y;
    y = should_carry &lt;&lt; <span class="hljs-number">1</span>;
  }
  <span class="hljs-keyword">return</span> x;
}
<span class="hljs-variable language_">console</span>.<span class="hljs-title function_">log</span>(<span class="hljs-title function_">add</span>(<span class="hljs-number">27</span>,<span class="hljs-number">15</span>));