title: C++ convert boost multiprecision int to 64 bit length hex
body: <p>lets imagine that we have code:</p>
  
  <pre><code>boost::multiprecision::mpz_int one(1);
  </code></pre>
  
  <p>and I would like to convert that value to 64 bit (?) hex value so the result could be:</p>
  
  <pre><code>0000000000000000000000000000000000000000000000000000000000000001
  </code></pre>
  
  <p>I'm sure that the is solution of that but I'm not familiar with Boost</p>
  
  <p>Example:
  I have value:</p>
  
  <pre><code>boost::multiprecision::mpz_int value(8612844778121073626993440829679478604092771119379437256704)
  </code></pre>
  
  <p>and I want create 64b hex from value,</p>
  
  <p>I tried </p>
  
  <pre><code>printf("%064X\n", value);
  </code></pre>
  
  <p>but don't work</p>