title: Best method to convert byte-array's elements to binary
body: <p>I am making a program where I have to read approx. 4,140,000 bytes in a single file 4mb (with hundreds of files to be read daily, which I stored in a <code>byte[]</code> array). Each of those bytes have to be converted to binary so that I may be able to access them on bit level. Currently, each time when the program needs to access a byte, it calls a function which converts that <code>arr[byteIndex]</code> into a binary string by executing following line:</p>
  
  <pre><code>return binary.Append(Convert.ToString(arr[byteIndex], 2).PadLeft(8, '0'));
  </code></pre>
  
  <p>The function is called millions of times. I want to make the program run faster. What is the best method/procedure I can use for time optimization.</p>