title: the extension of a source file
body: <p>A compiler checks the syntax of source code from the text file. Why is it necessary to save it with an extension <code>.c</code> or <code>.cpp</code>?</p>
  
  <p>I tried this on gcc but it does not compile a file with an extension other than <code>.c</code> and <code>.cpp</code>!!</p>