title: Printf big double value with high precision in C
body: <p>How to print big double value with precision of 10 in C-language (C99) ?</p>
  
  <pre><code>double d1 = 1100200300400500600.0000000001;
  double d2 = 1100200300400500600.0000000001;
  double d3 = d1 + d2;
  printf("???", d3);
  </code></pre>
  
  <p>Expect to have output: 2200400600801001200.0000000002</p>