title: Numerical precision of double type in Visual C++ 2008 Express debugger
body: <p>I'm using Visual C++ 2008 Express Edition and when i debug code:</p>
  
  <pre><code>double x = 0.2;
  </code></pre>
  
  <p>I see in debugging tooltip on x 0.20000000000000001</p>
  
  <p>but:</p>
  
  <pre><code>typedef numeric_limits&lt; double &gt; double_limit; 
  int a = double_limit::digits10
  </code></pre>
  
  <p>gives me: a = 15</p>
  
  <p>Why results in debugger are longer than normal c++ precision?
  What is this strange precision based on?</p>
  
  <p>My CPU is Intel Core 2 Duo T7100</p>