title: Add days to Date, and store new Date in String
body: <pre><code>DATA: l_str TYPE string,
      l_dat TYPE d.
  
  l_dat = sy-datum.
  l_str = l_dat.
  WRITE:/ l_str.
  
  l_dat = ( sy-datum + 1 ).
  l_str = l_dat.
  WRITE:/ l_str.
  l_dat = sy-datum.
  
  l_dat = ( l_dat + 1 ).
  l_str = l_dat.
  WRITE:/ l_str.
  
  l_dat = sy-datum.
  l_str = ( l_dat + 1 ).
  WRITE:/ l_str.
  </code></pre>
  
  <p>Result in the output (specifically the last line):</p>
  
  <pre><code>  20130222
    20130223
    20130223
    734909
  </code></pre>
  
  <p>And what is the best way to do this instead so as always to get the expected values?</p>