title: fopen returns null - Perror prints Invalid argument
body: <p>The simple fopen operation seems to not work. perror returns - Invalid argument. What could be wrong.</p>
  
  <p>I have a ascii file called abc.dat in R:.</p>
  
  <pre><code>int main()
  {
      FILE *f = fopen("R:\abc.dat","r");
      if(!f)
      {
          perror ("The following error occurred");
  
          return 1;
      }
  }
  </code></pre>
  
  <p>Output:</p>
  
  <blockquote>
    <p>The following error occurred: Invalid argument.</p>
  </blockquote>