Redis ZCARD command returns the number of elements stored in a set at a specified key.
Integer reply, the cardinality (number of elements) of the sorted set, or 0 if the key does not exist.
Following is the basic syntax of Redis ZCARD command.
redis 127.0.0.1:6379> ZCARD KEY_NAME
redis 127.0.0.1:6379> ZADD myset 1 "hello" (integer) 1 redis 127.0.0.1:6379> ZADD myset 1 "foo" (integer) 1 redis 127.0.0.1:6379> ZADD myset 2 "world" 3 "bar" (integer) 2 redis 127.0.0.1:6379> ZCARD myzset (integer) 4