(PECL wincache >= 1.1.0)
wincache_ucache_exists — Checks if a variable exists in the user cache
   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.
      
示例 #1 Using wincache_ucache_exists()
<?php
if (!wincache_ucache_exists('green'))
    wincache_ucache_set('green', 1);
var_dump(wincache_ucache_exists('green'));
?>以上示例会输出:
bool(true)
