loop that will output in order from 1 to 5 []bytes in golang

huangapple
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英文:

loop that will output in order from 1 to 5 []bytes in golang

问题

如何创建一个循环，按顺序输出从1到5个字节的内容？

以下是我需要的输出：

  1. [0]
  2. [1]
  3. [2]
  4. ...
  5. [255]
  6. [0 1]
  7. [1 1]
  8. [2 1]
  9. ...
  10. 等等（最多5个字节）

例如，如果我使用以下函数将数字转换为字节，并进行正常的循环：

  1. for i := 0; i < 8589934590; i++ {
  2.     b := intToBytes(i)
  3.     fmt.Println(b)
  4. }
  6. func intToBytes(val int) []byte {
  7.     r := make([]byte, 5)
  8.     for i := int(0); i < 5; i++ {
  9.         r[i] = byte((val >> (8 * i)) & 0xff)
  10.     }
  11.     return r
  12. }

输出的末尾会有额外的零。

如果要去除额外的零，可以尝试以下选项是否正确：

英文:

How to make a loop that will output in order from 1 to 5 []bytes?

Here is what I need in the output:

  1. [0]
  2. [1]
  3. [2]
  4. ...
  5. [255]
  6. [0 1]
  7. [1 1]
  8. [2 1]
  9. ...
  10. etc (to max 5 bytes)

For example, if I doing a normal loop from numbers and turn them into bytes using these functions:

  1. for i := 0; i &lt; 8589934590; i++ {
  2.     b : intToBytes(i)
  3.     fmt.Println(b)
  4. }
  6. func intToBytes(val int) []byte {
  7.     r := make([]byte, 5)
  8.     for i := int(0); i &lt; 5; i++ {
  9.         r[i] = byte((val &gt;&gt; (8 * i)) &amp; 0xff)
  10.     }
  11.     return r
  12. }

there will be extra zeros at the end of the output.

If this option is correct, then how to get rid of extra zeros?

答案1

得分: 1

这是一个解决方案。使用append函数来更新字节切片的长度。当移位结果为零时停止。

  1. package main
  3. import "fmt"
  5. func intToBytes(val int) []byte {
  6.     b := make([]byte, 0, 5)
  7.     for i := range b[:cap(b)] {
  8.         v := val >> (8 * i)
  9.         if v == 0 && i != 0 {
  10.             break
  11.         }
  12.         b = append(b, byte(v))
  13.     }
  14.     return b
  15. }
  17. func main() {
  18.     for i := 0; i < 4; i++ {
  19.         b := intToBytes(i)
  20.         fmt.Println(b)
  21.     }
  22.     fmt.Println("...")
  23.     for i := 260 - 8; i < 260; i++ {
  24.         b := intToBytes(i)
  25.         fmt.Println(b)
  26.     }
  27.     fmt.Println("...")
  28.     for i := 8589934590 - 4; i < 8589934590; i++ {
  29.         b := intToBytes(i)
  30.         fmt.Println(b)
  31.     }
  32. }

[0]
[1]
[2]
[3]
...
[252]
[253]
[254]
[255]
[0 1]
[1 1]
[2 1]
[3 1]
...
[250 255 255 255 1]
[251 255 255 255 1]
[252 255 255 255 1]
[253 255 255 255 1]

你可以在这里查看代码的运行结果：链接

英文:

Here is a solution. Use append to update the byte slice length. Stop when the shifted result is zero.

  1. package main
  3. import &quot;fmt&quot;
  5. func intToBytes(val int) []byte {
  6. 	b := make([]byte, 0, 5)
  7. 	for i := range b[:cap(b)] {
  8. 		v := val &gt;&gt; (8 * i)
  9. 		if v == 0 &amp;&amp; i != 0 {
  10. 			break
  11. 		}
  12. 		b = append(b, byte(v))
  13. 	}
  14. 	return b
  15. }
  17. func main() {
  18. 	for i := 0; i &lt; 4; i++ {
  19. 		b := intToBytes(i)
  20. 		fmt.Println(b)
  21. 	}
  22. 	fmt.Println(&quot;...&quot;)
  23. 	for i := 260 - 8; i &lt; 260; i++ {
  24. 		b := intToBytes(i)
  25. 		fmt.Println(b)
  26. 	}
  27. 	fmt.Println(&quot;...&quot;)
  28. 	for i := 8589934590 - 4; i &lt; 8589934590; i++ {
  29. 		b := intToBytes(i)
  30. 		fmt.Println(b)
  31. 	}
  32. }

https://go.dev/play/p/b91oYBpOw_Y

  1. [0]
  2. [1]
  3. [2]
  4. [3]
  5. ...
  6. [252]
  7. [253]
  8. [254]
  9. [255]
  10. [0 1]
  11. [1 1]
  12. [2 1]
  13. [3 1]
  14. ...
  15. [250 255 255 255 1]
  16. [251 255 255 255 1]
  17. [252 255 255 255 1]
  18. [253 255 255 255 1]

huangapple
  • 本文由 发表于 2022年2月18日 05:58:39
  • 转载请务必保留本文链接：https://go.coder-hub.com/71165892.html
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