title: How to read multi digit numbers in brainfuck
body: <p>I want to read in a number with any number of digits with bf. I know how to read in the correct number of digits if I set it manually, like this:</p>
  
  <pre><code>,&gt;,&gt;, 2 Read in 3 digits
  &lt;&lt; 0
  --------
  --------
  --------
  --------
  --------
  -------- 45 decrements
  &gt; 1
  --------
  --------
  --------
  --------
  --------
  --------
  &gt; 2
  --------
  --------
  --------
  --------
  --------
  --------
  
  [&gt;+&lt;-]&lt; 1 Copy digit 3 to cell 3
  
  [&gt;&gt;++++++++++&lt;&lt;-]&lt; Copy 10 * digit 2 to cell 3
  
  Copy 100 * digit 1 to cell 3
  [&gt;&gt;&gt;&gt;++++++++++ 4
      [&lt;++++++++++&gt;-] 4
  &lt;&lt;&lt;&lt;-]&gt;&gt;&gt; 3
  
  &gt;++++++++++..&lt; Add 2 line breaks
  
  ., Print and Pause
  </code></pre>
  
  <p>But I'd rather be able to set a number in <code>cell 0</code> and then automatically multiply the right number of times for each digit. What would I be best off doing?</p>