title: loop structure in mathematica
body: <p>Thanks for answering the previous question had before, i did the following, but i am trying to execute this loop, but there is no error given. I am trying to do date difference.</p>
  
  <pre><code>In[7] = Import["testA.txt", "Table" , "HeaderLines" -&gt; 1]
  Out[7] = {{100, 2010, 2, 20, 2010, 8, 30}, {110, 2010, 4, 30, 2010, 9, 
             12}, {112, 2010, 8, 20, 2010, 10, 28}}
  
  In[10] =  For[i = 1, i &lt; 4,   
            i = i + 1, {a = Out[7] [[i, 2]], b = Out[7] [[i, 3]],   
            c = Out[7] [[i, 4]] , d = Out[7][[i, 5]], e = Out[7][[i, 6]],   
            f = Out[7][[i, 7]], DateDifference[{a, b, c}, {d, e, f}]}]  
  </code></pre>