title: linux function setenv and putenv
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/5873029/questions-about-putenv-and-setenv">Questions about putenv() and setenv()</a>  </p>
  </blockquote>
  
  
  
  <p>As we know,we can use function <strong>setenv</strong> and <strong>putenv</strong> to change environment variables.What are their differences? Do they need to allocate memory or not?</p>
  
  <p>Thanks a lot.</p>