(PECL apcu >= 4.0.0)
apcu_cas — Updates an old value with a new value
$key, int $old, int $new): bool
apcu_cas() updates an already existing integer value if the
old parameter matches the currently stored value
with the value of the new parameter.
keyThe key of the value being updated.
oldThe old value (the value currently stored).
newThe new value to update to.
成功時(shí)返回 true， 或者在失敗時(shí)返回 false。
示例 #1 apcu_cas() example
<?php
apcu_store('foobar', 2);
echo '$foobar = 2', PHP_EOL;
echo '$foobar == 1 ? 2 : 1 = ', (apcu_cas('foobar', 1, 2) ? 'ok' : 'fail'), PHP_EOL;
echo '$foobar == 2 ? 1 : 2 = ', (apcu_cas('foobar', 2, 1) ? 'ok' : 'fail'), PHP_EOL;
echo '$foobar = ', apcu_fetch('foobar'), PHP_EOL;
echo '$f__bar == 1 ? 2 : 1 = ', (apcu_cas('f__bar', 1, 2) ? 'ok' : 'fail'), PHP_EOL;
apcu_store('perfection', 'xyz');
echo '$perfection == 2 ? 1 : 2 = ', (apcu_cas('perfection', 2, 1) ? 'ok' : 'epic fail'), PHP_EOL;
echo '$foobar = ', apcu_fetch('foobar'), PHP_EOL;
?>
以上例程的輸出類(lèi)似于：
$foobar = 2 $foobar == 1 ? 2 : 1 = fail $foobar == 2 ? 1 : 2 = ok $foobar = 1 $f__bar == 1 ? 2 : 1 = fail $perfection == 2 ? 1 : 2 = epic fail $foobar = 1