在Go中，如何确定切片在数组中的偏移量？

Question

I know that a1 is a slice within array a . Is it possible to determine offset of a1 with respect to beginning of a (basically emulating pointer arithmetics)?

a := [...]int8 {3,1,4,1,5,9,2,6,5,3,5,8,9,7,9,3,2}
a1 := a[3:14]
fmt.Println(a1, "has length", len(a1), "and offset", /*offset(a1,a)*/)

Answer 1

Here's one way to do it:

a := [...]int8{3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8, 9, 7, 9, 3, 2}
a1 := a[3:14]
fmt.Println(a1, "has length", len(a1), "and offset", cap(a)-cap(a1))

The expression a[p:e] returns a slice with capacity equal to cap(a) - p . Given the slice a1 and backing array a , you can compute p as p = cap(a) - cap(a1)

playground example