Come ottenere l'ultimo elemento di una fetta?

167

Qual è il modo Go per estrarre l'ultimo elemento di una sezione?

var slice []int

slice = append(slice, 2)
slice = append(slice, 7)

slice[len(slice)-1:][0] // Retrieves the last element

La soluzione sopra funziona, ma sembra imbarazzante.

go slice

— Morgan Wilde
fonte

297

For just reading the last element of a slice:

sl[len(sl)-1]

For removing it:

sl = sl[:len(sl)-1]

See this page about slice tricks

— Toni Cárdenas
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Thanks a bunch! Even though it does seem silly they didn't add the -1 index Python has...

— Morgan Wilde

I do like the -1 from Python, although it often lead to hard-to-debug errors.

— weberc2

They left it outside consciously. It was non-obvious and prone to errors. Go overall is circumspect about 'too much meaning'; it also doesn't feature method/operator overloading, default values for function params, etc. which IMHO goes in a similar philosophical vein. See this discussion and others: groups.google.com/forum/#!topic/golang-nuts/yn9Q6HhgWi0

— Toni Cárdenas

I am not sure but I got panic: runtime error: index out of range for profiles[len(profiles)-1].UserId, I guess the length of the slice is 0 so it panics?

— tom10271

@tom10271 Yes, you can't get the last element of a slice if there's no such element, ie. if there are no elements at all.

— Toni Cárdenas

-10

Bit less elegant but can also do:

sl[len(sl)-1: len(sl)]

— ccdrm
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That's the same as sl[len(sl)-1:], but that returns a slice containing the last element, rather than just the last element. play.golang.org/p/kcThrqa-64c

— Victor