golang：什么是字符串的零？

发布时间：2020-12-16 18:11:43 所属栏目：大数据来源：网络整理

导读：func NewKey(c appengine.Context,kind,stringID string,intID int64,parent *Key) *Key 文档说： NewKey creates a new key. kind cannot be empty. Either one or both of stringID and intID must be zero . If both are zero,the key returned is incomp

func NewKey(c appengine.Context,kind,stringID string,intID int64,parent *Key) *Key

文档说：

NewKey creates a new key. kind cannot be empty. Either one or both of
stringID and intID must be zero. If both are zero,the key
returned is incomplete. parent must either be a complete key or nil.

字符串的零是什么？

我试过0和nil，我得到错误像：

cannot use nil as type string in function argument

那是 ”” ：

var s string
fmt.Println(s=="") // prints "true"

字符串不能为nil(但是*字符串可以)。

你可以简单测试

if stringId=="" {

要在stringID中传递零字符串，请使用

k := NewKey(c,"kind","",p)

从the specification：

When memory is allocated to store a value,either through a
declaration or a call of make or new,and no explicit initialization
is provided,the memory is given a default initialization. Each
element of such a value is set to the zero value for its type: false
for booleans,0 for integers,0.0 for floats,“” for strings,and nil for pointers,functions,interfaces,slices,channels,and maps.

（编辑：李大同）

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