[ Editor's Note: The segfault has been fixed and will not occur in PHP 4.3.4 or PHP 5.0.0 when they are released.  However, it is still important to escape special characters as detailed below. ]

If your DN contains < or > characters, you must escape them with a backslash or ldap_explode_dn() will give you a "wrong parameter count" error or even a segmentation fault.

For example, these calls will fail with a "wrong parameter count" or a seg fault:

  ldap_explode_dn( "cn=<bob>,dc=example,dc=com", 0 );
  ldap_explode_dn( 'cn=<bob>,dc=example,dc=com', 0 );

But this will succeed

  ldap_explode_dn( "cn=\<bob\>,dc=example,dc=com", 0 );

Notice also that the < and > are escaped with hex codes as noted above. This function is a nice wrapper that properly formats all DNs and can safely be called with < and > characters, and UTF-8 characters:

function my_explode_dn( $dn, $with_attributes=0 )
{
        $dn = addcslashes( $dn, "<>" );
        $result = ldap_explode_dn( $dn, $with_attributes );
        //translate hex code into ascii again
        foreach( $result as $key => $value )
                $result[$key] = preg_replace("/\\\([0-9A-Fa-f]{2})/e", "''.chr(hexdec('\\1')).''", $value);
        return $result;
}

I am using php 4.3.1. Good luck!