# wincache_ucache_exists

(PECL wincache >= 1.1.0)

wincache_ucache_exists — Checks if a variable exists in the user cache

### 说明

wincache_ucache_exists ( string `$key` ) : bool

Checks if a variable with the `key` exists in the user cache or not.

### 参数

`key`

  The `key` that was used to store the variable in the cache. `key` is case sensitive.

### 返回值

Returns `TRUE` if variable with the `key` exitsts, otherwise returns `FALSE`.

### 范例

Example #1 Using wincache_ucache_exists()

    <?php
    if (!wincache_ucache_exists('green'))
        wincache_ucache_set('green', 1);
    var_dump(wincache_ucache_exists('green'));
    ?>

以上例程会输出：

    bool(true)

### 参见

- wincache_ucache_set() - Adds a variable in user cache and overwrites a variable if it already exists in the cache
- wincache_ucache_add() - Adds a variable in user cache only if variable does not already exist in the cache
- wincache_ucache_get() - Gets a variable stored in the user cache
- wincache_ucache_clear() - Deletes entire content of the user cache
- wincache_ucache_delete() - Deletes variables from the user cache
- wincache_ucache_meminfo() - Retrieves information about user cache memory usage
- wincache_ucache_info() - Retrieves information about data stored in the user cache