title: c++ scientific notation, change the digits of exponent
body: <p>I am using this code to output a scientific notation number to a file: </p>
  
  <pre><code>file &lt;&lt; scientific &lt;&lt; setprecision(10) &lt;&lt; num &lt;&lt; endl;
  </code></pre>
  
  <p>For example, if the number is 3.0, I get 3.0000000000E+00 from the code. How do I make the digits of the exponent part to be 3 digits? I want to get 3.0000000000E+000.</p>