title: What does the constant E do in the c language
body: <p>When I run the code below</p>
  
  <pre><code>int main(int argc,char *argv[]) {
      double n = 2E-1;
      printf("%d",n);
  }
  </code></pre>
  
  <p>When I run the code it prints a weird number instead of 0.2(2E-1).</p>