title: Convert integers to strings to create output filenames at run time
body: <p>I have a program in Fortran that saves the results to a file. At the moment I open the file using </p>
  
  <pre><code>OPEN (1, FILE = 'Output.TXT')
  </code></pre>
  
  <p>However, I now want to run a loop, and save the results of each iteration to the files <code>'Output1.TXT'</code>, <code>'Output2.TXT'</code>, <code>'Output3.TXT'</code>, and so on.</p>
  
  <p>Is there an easy way in Fortran to constuct filenames from the loop counter <code>i</code>?</p>