a := [...]int{5, 4: 1, 0, 2: 3, 2, 1: 4 }
fmt.Println(a)
the result is [5 4 3 2 1 0]. How it's sort?
a := [...]int{5, 4: 1, 0, 2: 3, 2, 1: 4 ,12,11,10}
fmt.Println(a)
the result is
prog.go:8: duplicate index in array literal: 2
prog.go:8: duplicate index in array literal: 3
prog.go:8: duplicate index in array literal: 4
[process exited with non-zero status]
Who can explain the both result?
I saw Dave Cheney tweet this the other day. My understanding is this:
The <number_here>: is an index in the array. This "sets" the current index.. which is why further into the declaration the index must be "reset" back in the array. So, the first number is 5 (index 0), the second "entry" has an index of 4: .. so the value 1 will be at index 4:
5 _ _ _ 1 _
^ index is currently here
..the next one has no index but it will continue after the last index given. which is 4+1 .. so index 5 gets the value 0:
5 _ _ _ 1 0
^ index is here.. it needs to be reset
Now the index will overrun .. so its gets set further back. The next one is 2: .. so that puts the value below with the value 3:
5 _ 3 _ 1 0
^ index is here
Next one again, continues on, since it has no index:
5 _ 3 2 1 0
^ index is here
Then the last one has index 1: .. with the value 4:
5 4 3 2 1 0
The second one is the same thing - but you haven't protected the over-writing of a currently placed index. Lets step through it:
Value 5 at index 0:
5 _ _ _ _ _ _ _ _
^ index is here
Value 1 at index 4:
5 _ _ _ 1 _ _ _ _
^ index is here
Value 0 at index 5 (remember, it continues on):
5 _ _ _ 1 0 _ _ _
^ index is here
Value 3 at index 2:
5 _ 3 _ 1 0 _ _ _
^ index is here
Value 2 at index 3 (again, it continues on:
5 _ 3 2 1 0 _ _ _
^ index is here
Value 4 at index 1:
5 4 3 2 1 0 _ _ _
^ index is here ... you're awfully close to overwriting the next value
Value 12 at index 2:
5 4 12 2 1 0 _ _ _
^^^^^ BOOOM
..you've overwritten the value 3 and will continue to do so given where the index is for the remaining values. This is the problem..
