title: Define union that can access bits, nibbles, bytes
body: <pre><code>union bits {
     unsigned int a : 1;
      unsigned int b : 2;
      unsigned int c : 3;
      unsigned int d : 4;``
      unsigned char x[2];
      unsigned int z; 
  };
  </code></pre>
  
  <p>Suppose in a union of 32 bits, 
  i need to  use a single bit, or a group of bits, or nibble, or bytes. is there a way to define the union.</p>