If memcached is working, calling memcache_connect( ) returns an Object instance, not a boolean. If memcached is not working, calling memcache_connect( ) throws a notice AND a warning (and returns false as expected). 

<?php
/* memcache is running */
$test1 = memcache_connect('127.0.0.1',11211);
echo gettype($test1);
// object
echo get_class($test1);
// Memcache

/* memcached is stopped */
$test2 = memcache_connect('127.0.0.1',11211);

/*
Notice: memcache_connect(): Server 127.0.0.1 (tcp 11211) failed with: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
 (10060) in C:\Program Files\Support Tools\- on line 1

Warning: memcache_connect(): Can't connect to 127.0.0.1:11211, A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
 (10060) in C:\Program Files\Support Tools\- on line 1
*/

echo gettype($test2);
// boolean
echo $test2===false;
// 1
?>

There appears to be no way to check whether memcached is actually running without resorting to error suppression:

<?php
$test3 = @memcache_connect('127.0.0.1',11211);
if( $test3===false ){
   // memcached is _probably_ not running
}
?>