以下Go数组操作起什么作用？

Question

I am confused about how the following code works, especially what is the purpose of "..."

array = append(array[:i], array[i+1:]...)

Answer 1

The line

a = append(a[:i], a[i+1:]...)

creates a new slice by removing the item at position i in a, by combining the items from 0 to i (not included), and from i+1 to the end.

Your second question is what is the purpose of .... append accepts a slice as first argument, and an unlimited number of arguments, all with a type assignable to the type of its elements.

append is defined as

func append(slice []Type, elems ...Type) []Type

Writing

a = append(a[:i], a[i+1:]...)

is equivalent as writing

a = append(a[:i], a[i+1], a[i+2], a[i+3], a[i+4]) //and so on, until the end of the slice.

Using a[i+1:]... is basically a shorthand syntax, as the Go spec describes in https://golang.org/ref/spec#Passing_arguments_to_..._parameters:

If f is variadic with a final parameter p of type ...T, then within f the type of p is equivalent to type []T. If f is invoked with no actual arguments for p, the value passed to p is nil. Otherwise, the value passed is a new slice of type []T with a new underlying array whose successive elements are the actual arguments, which all must be assignable to T

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