(PECL memcache >= 0.2.0)
Memcache::increment — Increment item's value
Memcache::increment() increments value of the item on the specified value . If item with key key was not numeric and cannot be converted to number, it will change it's value to value . Memcache::increment() does not create an item if it didn't exist.
Note: Do not use Memcache::increment() with item, which was stored compressed, because consequent call to Memcache::get() will fail.
Also you can use memcache_increment() function.
Key of the item to increment.
Increment the item by value . Optional and defaults to 1.
Returns new item's value on success or FALSE on failure.
Example #1 Memcache::increment() example
<?php
/* procedural API */
$memcache_obj = memcache_connect('memcache_host', 11211);
/* increment counter by 2 */
$current_value = memcache_increment($memcache_obj, 'counter', 2);
/* OO API */
$memcache_obj = new Memcache;
$memcache_obj->connect('memcache_host', 11211);
/* increment counter by 3 */
$current_value = $memcache_obj->increment('counter', 3);
?>