(PECL wincache >= 1.1.0)
wincache_ucache_exists — Checks if a variable exists in the user cache
$key
   )
   Checks if a variable with the key exists in the user cache or not.
  
key
       The key that was used to store the variable in the cache. 
       key is case sensitive.
      
   Returns TRUE if variable with the key exitsts, 
   otherwise returns FALSE.
  
Пример #1 Using wincache_ucache_exists()
<?php
if (!wincache_ucache_exists('green'))
    wincache_ucache_set('green', 1);
var_dump(wincache_ucache_exists('green'));
?>
Результат выполнения данного примера:
bool(true)