title: Decrementing an iterator until the .begin() of a vector
body: <p>I need to read a vector backward from a certain position of an iterator, and put up to n1 values in the dictionnary array. </p>
  
  <p>I though about making a loop and decrementing the iterator, but for some reasons I'm stuck in an infinite loop.</p>
  
  <p>I think there's an issue in the while condition? </p>
  
  <pre><code>//I read all the vSignal vector
  while (vSignalIt != vSignal.end()) {
  
      i = 0;
      vSignalIt2 = vSignalIt;
  
      //Filling the dictionnary array
      if (vSignalIt != vSignal.begin()) {
          do 
          {
              dictionnary[i] = *vSignalIt2;
              vSignalIt2--;
              i++;
          } while (vSignalIt2 != vSignal.begin() || i &lt; (uint8_t)n1);
      }
  
      //Do something with the value of dictionnary and increase vSignalIt to advance forward in the vSignal vector
  
  }
  </code></pre>