(no version information, might be only in CVS)
Memcache::decrement -- Decrement item's value
Description
int 
Memcache::decrement ( string key [, int value] )
   Memcache::decrement() decrements value of the 
   item by value. Similarly to 
   Memcache::increment(), current value of the item is
   being converted to numerical and after that value
   is substracted. 
   
Note: 
     New item's value will not be less than zero.
    
 
   Note: 
     Do not use Memcache::decrement() with item, which was
     stored compressed, because consequent call to 
     Memcache::get() will fail.
    
 
   Memcache::decrement() does not
   create an item if it didn't exist.
   Also you can use 
memcache_decrement() function.