title: How to combine number and string in batch file
body: <p>I am using batch file to display some kind of number such as
  00_test.txt 01_test.txt...10_test.txt 11_test.txt
  Hence, This is my code. But I cannot show as my expectation</p>
  
  <pre><code>FOR /L %%x IN (1,1,10) DO (
  set "extension=.txt" 
  set "fullname=%x%_test%extension%" 
  echo.%fullname%
  )
  </code></pre>
  
  <p>The result of above code are <code>_test.txt  _test_txt</code> but expected result are </p>
  
  <pre><code>00_test.txt 01_test.txt
  </code></pre>
  
  <p>Could you help me edit it?</p>