初始化切片 s := make([]int, 3) 取 s[3:] 不会报越界错误，取 s[4:]就会越界了， 求教啊
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1
Leigg Oct 3, 2019 via Android
这个还真没碰见过，是冷知识？
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c0011 Oct 3, 2019
s[3:] 是扩展切片，3 代表的是个数不是下标。
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c0011 Oct 3, 2019
我上边的不对。可能就是语言的规定吧，3 代表最后一个元素并且是空(nil?)
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kidlj Oct 3, 2019
> For arrays or strings, the indices are in range if 0 <= low <= high <= len(a), otherwise they are out of range. For slices, the upper index bound is the slice capacity cap(a) rather than the length.
ref: https://golang.org/ref/spec#Slice_expressions 原因未知 :) |
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kidlj Oct 3, 2019  3
> The indices low and high select which elements of operand a appear in the result. The result has indices starting at 0 and length equal to high - low
> For convenience, any of the indices may be omitted. A missing low index defaults to zero; a missing high index defaults to the length of the sliced operand. 因此 s[3:] == s[3:len(a)] = s[3:3] ✓ s[4:] == s[4:len(a)] == s[4:3] x |
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kidlj Oct 3, 2019 1
@c0011
> the index x is in range if 0 <= x < len(a), otherwise it is out of range ref: https://golang.org/ref/spec#Index_expressions |
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kidlj Oct 3, 2019
修正：len(s) 不是 len(a)
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gamexg Oct 3, 2019 via Android 1
故意的吧，
如果 s[3:]就报错，就无法取末尾的空切片了。 |
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Vegetable Oct 3, 2019
错误信息是
panic: runtime error: slice bounds out of range [4:3] 6 楼说的应该就是正确答案了. |
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shijiu Oct 3, 2019
缺少的最高位是切片长度，而最高位是开区间，取 s[3:3]的话返回一个 0 长切片，应该是一个规定吧，方便判断。
就和 s[:0]返回一个 0 长切片一样？ |
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13
Carseason Oct 4, 2019
s[3:3]
s[4:3] |
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