ZINCRBY

有序集合中指定成員的分?jǐn)?shù)加上增量increment，正負(fù)均可。

Command

127.0.0.1:6379> zadd animal 1 cat
(integer) 1
// 返回加上增量后的結(jié)果
127.0.0.1:6379> ZINCRBY animal 1 cat
"2"
// 當(dāng)member不存在時(shí)，以增加為分?jǐn)?shù)，增加member，返回增量
127.0.0.1:6379> ZINCRBY animal 2 dog
"2"
// 以浮點(diǎn)數(shù)作為增量
127.0.0.1:6379> ZINCRBY animal 1.1 cat
"3.1000000000000001"

但是為社么以浮點(diǎn)數(shù)作為增量時(shí)，member的分?jǐn)?shù)變成了很長的浮點(diǎn)數(shù)？但是最后go代碼里得出的結(jié)果卻精確到了想要的結(jié)果？

有一個(gè)相關(guān)的issue解釋了，https://github.com/antirez/redis/issues/1499,大致是這樣子不影響排序，但是展示出來的就是這樣長

Code

func zincrby(c redis.Conn) {
    defer c.Do("DEL", "animal")
    c.Do("ZADD", "animal", 1, "cat")
    newScore, _ := redis.Int(c.Do("ZINCRBY", "animal", 1, "cat"))
    fmt.Println("New score of member is:", newScore)
    newScore, _ = redis.Int(c.Do("ZINCRBY", "animal", 2, "dog"))
    fmt.Println("New score of new member is:", newScore)
    newScoreFloat, _ := redis.Float64(c.Do("ZINCRBY", "animal", 1.1, "cat"))
    fmt.Println("When increment is float, new score of member is:", newScoreFloat)
}

Output

$ go run main.go
New score of member is: 2
New score of new member is: 2
When increment is float, new score of member is: 3.1