切片在 GO 中是如何工作的？

Question

a = make([]int, 7, 15)

creates implicit array of size 15 and slice( a ) creates a shallow copy of implicit array and points to first 7 elements in array.

Consider,

var a []int;

creates a zero length slice that does not point to any implicit array.

a = append(a, 9, 86);

creates new implicit array of length 2 and append values 9 and 86 . slice( a ) points to that new implicit array, where

len(a) is 2 and cap(a) >= 2

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My question:

is this the correct understanding?

Answer 1

As I mentioned " Declare slice or make slice? ", the zero value of a slice (nil) acts like a zero-length slice.

So you can append to a []int directly.

You would need to make a slice ( make([]int, 0) ) only if you wanted to potentially return an empty slice (instead of nil ).
If not, no need to allocate memory before starting appending.
See also " Arrays, slices (and strings): The mechanics of 'append': Nil "

a nil slice is functionally equivalent to a zero-length slice, even though it points to nothing. It has length zero and can be appended to, with allocation.