On Tue, Nov 10, 2020 at 8:12 PM 'Kilos' via golang-nuts < golang-nuts@googlegroups.com> wrote:
> For Kurtis: > I know the map will choose random hash seed to init itself, and the > iterator will also choose random order to iterate map. > And I know it is a bad idea to add or delete a key when iterating a map, > but I want to know what causes the inpredictable result, not the key's > iterating order, but the key's count that was printed. > The count is wrong, sometimes, because you are relying on undefined behavior. Ignore the Go map implementation as it is irrelevant to your question. If Go's map implementation used something like a binary tree without mutating the keys (to make it hard to create a DOS attack) your example program would still behave unpredictably if you vary the keys. Repeat after me: You cannot safely mutate a Go map while iterating over it with the `range` operator. This is true for most map data structures in most, non-functional (e.g., Haskell), programming languages. -- Kurtis Rader Caretaker of the exceptional canines Junior and Hank -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CABx2%3DD84Q1%3DPjCJjxt9m7GLT7g%2B5E647bp7eu-vFs4Bu3TrMPw%40mail.gmail.com.
