## zRank, zRevRank ##### *Description* Returns the rank of a given member in the specified sorted set, starting at 0 for the item with the smallest score. zRevRank starts at 0 for the item with the *largest* score. 返回key对应的有序集合中member元素的索引值，元素按照score从低到高进行排列。rank值（或index）是从0开始的，这意味着具有最低score值的元素的rank值为0。使用ZREVRANK可以获得从高到低排列的元素的rank（或index）。 ##### *Parameters* *key* *member* ##### *Return value* *Long*, the item's score. ##### *Example* ``` <pre class="calibre9">$redis->delete('z'); $redis->zAdd('key', 1, 'one'); $redis->zAdd('key', 2, 'two'); $redis->zRank('key', 'one'); /* 0 */ $redis->zRank('key', 'two'); /* 1 */ $redis->zRevRank('key', 'one'); /* 1 */ $redis->zRevRank('key', 'two'); /* 0 */ ``` ##