Golang索引超出范围

huangapple
go评论110阅读模式
英文:

Golang index out of range

问题

我正在尝试制作一个简单的Golang示例。这个示例在Golang之旅的第36页上。

这是我的代码：

  1. package main
  3. import "code.google.com/p/go-tour/pic"
  4. import "fmt"
  6. func Pic(dx, dy int) [][]uint8 {
  7.     dx8 := uint8(dx)
  9.     s1 := make([][]uint8, dy)
  10.     fmt.Printf("%d\n", len(s1), cap(s1))
  12.     for i := range s1 {
  13.         fmt.Printf("%d\n", i)
  14.         for j := range s1 {
  15.             fmt.Printf("%d\n", j)
  16.             s1[i][j] = dx8
  17.         }
  18.     }
  20.     return s1
  21. }
  23. func main() {
  24.     pic.Show(Pic)
  25. }

我得到的错误是：

  1. 256
  2. %!(EXTRA int=256)0
  3. 0
  4. panic: runtime error: index out of range
  6. goroutine 1 [running]:
  7. panic(0x18b820, 0x1040a010)
  8.     /usr/local/go/src/runtime/panic.go:464 +0x700
  9. main.Pic(0x100, 0x100, 0x0, 0x0, 0x0, 0x0)
  10.     /tmp/sandbox716191956/main.go:17 +0x4e0
  11. code.google.com/p/go-tour/pic.Show(0x1d7988, 0x104000e0)
  12.     /go/src/code.google.com/p/go-tour/pic/pic.go:20 +0x60
  13. main.main()
  14.     /tmp/sandbox716191956/main.go:26 +0x20
  16. Program exited.

我只想返回一个二维切片，供Show函数使用。

英文:

I'm trying to make a simply example of Golang. The example it's in te 36º page of the tour of golang.
This is my code:

  1. package main
  3. import "code.google.com/p/go-tour/pic"
  4. import "fmt"
  6. func Pic(dx, dy int) [][]uint8 {
  7.     dx8 := uint8(dx)
  9.     s1 := make ([][] uint8, dy)
  10.     fmt.Printf("%d\n", len(s1), cap(s1))
  12.     for i := range s1{
  13.         fmt.Printf("%d\n",i)
  14.         for j := range s1 {
  15.             fmt.Printf("%d\n",j)
  16.             s1[i][j] = dx8    
  17.         }
  18.     }
  20.     return s1
  21. }
  23. func main() {
  24.     pic.Show(Pic)
  25. }

And the error I got:

  1.     256
  2. %!(EXTRA int=256)0
  3. 0
  4. panic: runtime error: index out of range
  6. goroutine 1 [running]:
  7. panic(0x18b820, 0x1040a010)
  8. 	/usr/local/go/src/runtime/panic.go:464 +0x700
  9. main.Pic(0x100, 0x100, 0x0, 0x0, 0x0, 0x0)
  10. 	/tmp/sandbox716191956/main.go:17 +0x4e0
  11. code.google.com/p/go-tour/pic.Show(0x1d7988, 0x104000e0)
  12. 	/go/src/code.google.com/p/go-tour/pic/pic.go:20 +0x60
  13. main.main()
  14. 	/tmp/sandbox716191956/main.go:26 +0x20
  16. Program exited.

I only want to return a bidimensial slice which Show function uses.

答案1

得分: 1

你需要为图片的两个维度 dy 和 dx 制作切片。例如，

  1. package main
  3. import "golang.org/x/tour/pic"
  5. func Pic(dx, dy int) [][]uint8 {
  6.     p := make([][]uint8, dy)
  7.     for i := range p {
  8.         p[i] = make([]uint8, dx)
  9.         for j := range p[i] {
  10.             p[i][j] = uint8(i * j)
  11.         }
  12.     }
  13.     return p
  14. }
  16. func main() {
  17.     pic.Show(Pic)
  18. }
英文:

You need to make the slices for both dimensions, dy and dx, of the picture. For example,

  1. package main
  3. import "golang.org/x/tour/pic"
  5. func Pic(dx, dy int) [][]uint8 {
  6. 	p := make([][]uint8, dy)
  7. 	for i := range p {
  8. 		p[i] = make([]uint8, dx)
  9. 		for j := range p[i] {
  10. 			p[i][j] = uint8(i * j)
  11. 		}
  12. 	}
  13. 	return p
  14. }
  16. func main() {
  17. 	pic.Show(Pic)
  18. }

答案2

得分: 0

你的代码中的问题是在第二个循环中循环的大小错误。
你的第二个循环的范围应该是s1[i]的大小，而不是s1，因为第二个循环处理的是内部维度。

  1. for i := range s1{
  2.     fmt.Printf("%d\n",i)
  3.     s1[i] = make([]uint8, dy)
  4.     for j := range s1[i] {
  5.         fmt.Printf("%d\n",j)
  6.         s1[i][j] = dx8
  8.     }
  9. }
英文:

The problem in your code you are looping in wrong size in the second loop.
your second range must be sieze of s1[i] not s1 because the second loop processes on inner dimension.

  1. for i := range s1{
  2.     fmt.Printf("%d\n",i)
  3.     s1[i] = make ([] uint8, dy)
  4.     for j := range s1[i] {
  5.         fmt.Printf("%d\n",j)
  6.         s1[i][j] = dx8
  8.     }
  9. }

huangapple
  • 本文由 发表于 2016年3月28日 19:03:36
  • 转载请务必保留本文链接：https://go.coder-hub.com/36260994.html
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