Golang sort.Swap方法

Question

I am fairly new to Golang, although I have already written some lines of code. I was exploring the sorting options when I found this^(src):

func (p StringSlice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }

I have no clue what is it going on there. Could someone explain to me what p[i], p[j] = p[j], p[i] is doing?

Thanks.

Answer 1

It does what its name says: it swaps the i^th and j^th elements.

It is an assignment, more specifically a tuple assignment:

p[i], p[j] = p[j], p[i]

It assigns values to p[i] and p[j], and the values that are assigned to them in order are p[j] and p[i].

The assignment proceeds in two phases. First, the operands of index expressions and pointer indirections (including implicit pointer indirections in selectors) on the left and the expressions on the right are all evaluated in the usual order. Second, the assignments are carried out in left-to-right order.