如何在Go中清除地图？ [英] How to clear a map in Go?

问题描述

我为基元类型 map 寻找类似c ++函数 .clear（）的东西。

或者我应该创建一个新的地图吗？

更新：感谢您的回答。通过查看答案，我才意识到有时创建新地图可能会导致我们不想要的一些不一致。考虑下面的例子：

  var a map [string] string 
 var b map [string] string 
 
 func main（）{
a = make（map [string] string）
b = a 
a [hello] =world
a = nil 
 fmt.Println（b [hello]）
} 
  

我的意思是，这仍然不同于c ++中的 .clear（）函数，它将清除对象中的内容。 >解决方案

你应该创建一个新的地图。除非相同的地图被多个代码片段引用，并且一个片段明确需要清除这些值，使得这些更改对于其他代码片段可见，否则没有真正的理由去试图清除现有的片段。 / p>

所以是的，你可能应该说

  mymap = make map [keytype] valtype）
  

---

无论出于何种原因，都需要清除现有地图，这很简单：

  for k：= range m {
删除（m，k）
} 
  

I'm looking for something like the c++ function .clear() for the primitive type map.

Or should I just create a new map instead?

Update: Thank you for your answers. By looking at the answers I just realized that sometimes creating a new map may lead to some inconsistency that we don't want. Consider the following example:

var a map[string]string
var b map[string]string

func main() {
    a = make(map[string]string)
    b=a
    a["hello"]="world"
    a = nil
    fmt.Println(b["hello"])
}

I mean, this is still different from the .clear() function in c++, which will clear the content in the object.

解决方案

You should probably just create a new map. There's no real reason to bother trying to clear an existing one, unless the same map is being referred to by multiple pieces of code and one piece explicitly needs to clear out the values such that this change is visible to the other pieces of code.

So yeah, you should probably just say

mymap = make(map[keytype]valtype)

---

If you do really need to clear the existing map for whatever reason, this is simple enough:

for k := range m {
    delete(m, k)
}

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