英文:
How to find next character in Golang?
问题
我只是出于对golang的兴趣而做一些算法问题。我知道在其他语言中，要找到下一个按字母顺序排列的字符，可以对字符进行位移操作，因为字符（比如在C语言中）实际上是一个数字。
所以我尝试了以下代码：
"a" >> 2
或类似的操作，但是出现了类型不匹配的错误。
我想知道如何实现这个功能。
英文:
I'm just doing some algorithms problems out of interest in golang. I understand that in other languages to find the next character alphabetically I can bitshift the character, as a character (I'm thinking of C) is really a number.
So I tried doing
"a" >> 2
Or something to that effect, but there is a type mismatch.
I'd like to know how I can achieve this.
答案1
得分: 3
我不确定你从哪里得到这个想法，认为这会给你“下一个字符”。这在任何语言中都是不正确的。'a' >> 2 的作用如下：
'a'被解释为int32(97)（示例）>>表示“将 X 向右移 Y 位”。将某个值向右移动 2 位与将其除以 4 的结果是相同的。因此，(x >> 2) == (x / 4)（示例）97 / 4 == 24。字符b的 ASCII 值为98。所以这并不能让你接近下一个字符（示例）
更多关于位移的内容
当考虑一个数的二进制表示时，位移操作最为明显。对于表达式 z = x >> y，我们可以注意到以下内容：
x(97): 01100001
y(2): 00000010
-------- >>
z(24): 00011000
注意，x 中的所有位都向右移动了两位。末尾掉落的 1 被丢弃了。
类似地，你可以进行“左移”操作（<<）。就像 x >> 1 等同于 x / 2，x << 1 等同于 x * 2。
表达式：5>>1 == 5/2 == 2：
x(5): 00000101
y(1): 00000001
-------- >>
z(2): 00000010
表达式：5<<1 == 5*2 == 10：
x(5): 00000101
y(1): 00000001
-------- <<
z(10): 00001010
实际获取下一个字符
如果你想要获取紧随 'a' 之后的字符，你只需要将其加 1，就像这个 示例 中所示。
英文:
I am not sure where you get the idea that this gives you the 'next character'. This is not true in any language. What 'a' >> 2 does is this:
- 'a' is interpreted as
int32(97)(example) >>means 'shift X right by Y bits'. Shifting something right by 2 bits is functionally the same as an integer divide by 4. So(x >> 2) == (x / 4). (example)97 / 4 == 24. Thebcharacter has ASCII value98. So this doesn't get you anywhere near. (example)
More on the bit shifting
Bit shifting is most obvious when considering a number in its binary notation. For the expression z = x >> y, we can note the following:
x(97): 01100001
y(2): 00000010
-------- >>
z(24): 00011000
Note that all the bits in x have simply been moved to the right by two bits. The 1 that fell off the end is dropped.
Similarly, you can 'shift left' (<<). Just like x >> 1 is the same as x / 2, x << 1 is the same as x * 2.
Expression: 5>>1 == 5/2 == 2:
x(5): 00000101
y(1): 00000001
-------- >>
z(2): 00000010
Expression: 5<<1 == 5*2 == 10:
x(5): 00000101
y(1): 00000001
-------- <<
z(10): 00001010
Actually getting the next character
If you want the character directly following 'a', you simply add 1 to it as evidenced in this example.
答案2
得分: 1
你正在尝试移动一个字符串，而不是一个字节，就像@Not_a_Golfer所说的'a'>>2应该可以正常工作。
然而，要获取下一个字符，你可以这样做：
func nextChar(ch byte) byte {
if ch += 1; ch > 'z' {
return 'a'
}
return ch
}
func main() {
fmt.Println(string(nextChar('a')))
}
当然，如果你需要的不仅仅是 a-z 的支持，那么会更加复杂。你可以查看 unicode 包和关于 Go 字符串的 这篇 博文。
英文:
You're trying to shift a string, not a byte, like @Not_a_Golfer said 'a'>>2 should work fine.
However to get the next character you can do something like:
func nextChar(ch byte) byte {
if ch += 1; ch > 'z' {
return 'a'
}
return ch
}
func main() {
fmt.Println(string(nextChar('a')))
}
Of course it'd be more complex if you need more than a-z support, take a look at the unicode package and this blog post about go strings.
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