(PECL apcu >= 4.0.0)
apcu_exists — Checks if entry exists
keysA string, or an array of strings, that contain keys.
Returns true if the key exists, otherwise false Or if an
array was passed to keys, then
an array is returned that contains all existing keys, or an empty
array if none exist.
Example #1 apcu_exists() example
<?php
$fruit = 'apple';
$veggie = 'carrot';
apcu_store('foo', $fruit);
apcu_store('bar', $veggie);
if (apcu_exists('foo')) {
echo "Foo exists: ";
echo apcu_fetch('foo');
} else {
echo "Foo does not exist";
}
echo PHP_EOL;
if (apcu_exists('baz')) {
echo "Baz exists.";
} else {
echo "Baz does not exist";
}
echo PHP_EOL;
$ret = apcu_exists(array('foo', 'donotexist', 'bar'));
var_dump($ret);
?>
以上例程的输出类似于：
Foo exists: apple
Baz does not exist
array(2) {
["foo"]=>
bool(true)
["bar"]=>
bool(true)
}