title: How to enter numbers in Forth
body: <p>Is there something like <code>input</code> in Basic or <code>scanf("%d")</code> in C in Forth?</p>
  
  <p>Probably it will be something like this:</p>
  
  <pre><code>200 buffer: buf
  : input ( -- n ) buf 200 accept 
    some-magic-filter
    buf swap evaluate ;
  </code></pre>
  
  <p>The problem in the above code, is how to define a filter that will pass only numbers, but not any words, definitions, etc?</p>