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go - Go 练习 #18 : Slices, 索引超出范围

转载 作者:IT王子 更新时间:2023-10-29 00:44:26 31 4
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我正在完成 Go 之旅中的练习,但遇到了一个我无法弄清楚的障碍。

我在做Exercise: Slices我收到了这个错误:

256 x 256

panic: runtime error: index out of range [0] with length 0

goroutine 1 [running]:
main.Pic(0x100, 0x100)
/tmp/sandbox1628012103/prog.go:14 +0xcf
golang.org/x/tour/pic.Show(0xc0000001a0)
/tmp/gopath962180923/pkg/mod/golang.org/x/tour@v0.0.0-20201207214521-004403599411/pic/pic.go:32 +0x28
main.main()
/tmp/sandbox1628012103/prog.go:25 +0x25

这是我的代码:

package main

import (
"fmt"
"golang.org/x/tour/pic"
)

func Pic(dx, dy int) [][]uint8 {
fmt.Printf("%d x %d\n\n", dx, dy)

pixels := make([][]uint8, 0, dy)

for y := 0; y < dy; y++ {
pixels[y] = make([]uint8, 0, dx)

for x := 0; x < dx; x++ {
pixels[y][x] = uint8(x * y)
}
}

return pixels
}

func main() {
pic.Show(Pic)
}

最佳答案

Slices

For a string, array, pointer to array, or slice a, the primary expression

a[low : high]

constructs a substring or slice. The index expressions low and high select which elements appear in the result. The result has indexes starting at 0 and length equal to high - low.

For arrays or strings, the indexes low and high must satisfy 0 <= low <= high <= length; for slices, the upper bound is the capacity rather than the length.

Indexes

A primary expression of the form

a[x]

denotes the element of the array, slice, string or map a indexed by x. The value x is called the index or map key, respectively. The following rules apply:

For a of type A or *A where A is an array type, or for a of type S where S is a slice type:

x must be an integer value and 0 <= x < len(a)

a[x] is the array element at index x and the type of a[x] is
the element type of A

if a is nil or if the index x is out of range, a run-time panic occurs

Making slices, maps and channels

make(T, n)       slice      slice of type T with length n and capacity n
make(T, n, m) slice slice of type T with length n and capacity m

y 必须是整数值且 0 <= y < len(pixel[]uint8)。 x 必须是整数值且 0 <= x < len(pixel[][]uint8)。例如,

package main

import "tour/pic"

func Pic(dx, dy int) [][]uint8 {
pixels := make([][]uint8, dy)
for y := 0; y < dy; y++ {
pixels[y] = make([]uint8, dx)
for x := 0; x < dx; x++ {
pixels[y][x] = uint8(x * y)
}
}
return pixels
}

func main() {
pic.Show(Pic)
}

关于go - Go 练习 #18 : Slices, 索引超出范围,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/11585008/

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