重新切片二维切片

Question

I came across a problem which needed editing several indexes of a 2-dimensional slice.

Imagine the following numbers as a 2-d slice of slices a [][]int

0 1 2 3
1 2 3 4
2 3 4 5
3 4 5 6

The problem is that I want to access and modify

0 1
1 2

As a sub-slice and I want a to be changed as well. I achieved that with this code :

sub := a[:2]
for i := range sub {
    sub[i] = sub[i][:2]
}

Now fmt.Println(sub) prints [[0 1] [1 2]] But the problem is fmt.Println(a) is printing [[0 1] [1 2] [2 3 4 5] [3 4 5 6]]

The question is, how can I access this sub-slice without losing any data?

Answer 1

If your goal to modify the original []int slice elements when using sub, then copy the elements of a to a new slice. The code in the question modifies a directly.

sub := make([][]int, 2)
for i := range sub {
    sub[i] = a[i][:2]
}