英文:
Use of variable in 'for' loop is not recognized in Go
问题
我正在开发Go语言，并运行以下for循环：
// 定义初始值
i := 0
for {
// 根据迭代获取随机数据
data, i := GiveRandomData(i)
// 保存到数据库
response, err := SaveToDatabase(data)
if err != nil { log.Fatal(err) }
fmt.Println(response)
}
然而，当编译这个程序时，我得到以下错误：
.\main.go:26: i declared and not used
Go编译器似乎没有意识到i变量在下一次循环中被返回给函数。在这个函数内部，i变量的值会改变。
我应该怎么做才能消除这个编译错误，或者让Go理解这个变量在这个无限for循环的下一次迭代中是被使用的呢？
英文:
I'm developing in Go and I run the following for loop:
// Define Initial Value
i := 0
for {
// Get random data based on iteration
data, i := GiveRandomData(i)
// Save to database
response, err := SaveToDatabase(data)
if err != nil { log.Fatal(err) }
fmt.Println(response)
}
However, when compiling this program, I get the following error:
> .\main.go:26: i declared and not used
The Go compiler doesn't seem to recognise that the i variable is given back to the function in the next loop. Inside this function, the I variable changes value.
What should I do to get rid of this compilation error or to let Go understand that this variable is not unused, but used in the next iteration of this endless for loop?
答案1
得分: 8
Go编译器似乎没有意识到在下一个循环中将i变量返回给函数。在这个函数内部，I变量的值发生了变化。
不，i的值没有改变；:=声明了一个新的i。（Go允许你这样做是因为data也是新的。）如果要给它赋值，你需要单独声明data：
var data RandomDataType
data, i = GiveRandomData(i)
或者给新的i一个临时名称：
data, next := GiveRandomData(i)
i = next
英文:
> The Go compiler doesn't seem to recognise that the i variable is given back to the function in the next loop. Inside this function, the I variable changes value.
No, i does not change value; := declares a new i. (Go allows you to do this because data is also new.) To assign to it instead, you’ll need to declare data separately:
var data RandomDataType
data, i = GiveRandomData(i)
Or give the new i a temporary name:
data, next := GiveRandomData(i)
i = next
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