Site redirection if page not found

PHP
1

Does anyone know some PHP code I could use to test if a website is down and if it is then redirect the current page to a designated page?

Basically the following flow needs to happen:

index.php is visited. As it opens up it check to see if site A is up. If so it proceeds to site A, if not it redirects to site B.

The redirection part is not a problem, I’m just needing some ideas on testing for the invalid or not working site.

2

Try this:



   $file=''http://sitepoint.com';

   $str = file_get_contents( $file );

    echo strlen($str);