为什么不能在Go的for循环中使用'var'？ [关闭]

Question

I'm new to Go, and there is a question.

As I know, the following two snippets are basically the same.

i := 0

var i = 0

but why can't var statement be used in for loop?

for var i = 0; i < 10; i++ {
    //do something
}

There will be a syntax error: var declaration not allowed in for initializergo

Why is it designed this way? Are there any thoughts in it?

I would appreciate it if someone could tell me.

Answer 1

The initialisation statement in this form of the for clause can't be any kind of statement but must be a "simple statement" (one case of such statements is the "short variable declaration" you saw working).

As for the reason, it's just like many other choices in the Go language: to keep your code readable and looking like the Go code of other developpers: if you could put any kind of statement here, the for loop wouldn't always be easily identifiable (and would mix concerns other than loop initialization).