string Golang 从符文转换为字符串

Golang converting from rune to string

提问by user3551708

I have the following code, it is supposed to cast a runeinto a stringand print it. However, I am getting undefined characters when it is printed. I am unable to figure out where the bug is:

我有以下代码，它应该将 arune转换为 astring并打印它。但是，我在打印时收到未定义的字符。我无法弄清楚错误在哪里：

package main

import (
    "fmt"
    "strconv"
    "strings"
    "text/scanner"
)

func main() {
    var b scanner.Scanner
    const a = `a`
    b.Init(strings.NewReader(a))
    c := b.Scan()
    fmt.Println(strconv.QuoteRune(c))
}

采纳答案by icza

That's because you used Scanner.Scan()to read a runebut it does something else. Scanner.Scan()can be used to read tokensor runes of special tokens controlled by the Scanner.Modebitmask, and it returns special constants form the text/scannerpackage, not the read rune itself.

那是因为你曾经Scanner.Scan()读过 arune但它做了别的事情。Scanner.Scan()可用于读取由位掩码控制的令牌或rune特殊令牌Scanner.Mode，它返回text/scanner包中的特殊常量，而不是读取符文本身。

To read a single runeuse Scanner.Next()instead:

改为读取单次rune使用Scanner.Next()：

c := b.Next()
fmt.Println(c, string(c), strconv.QuoteRune(c))

Output:

输出：

97 a 'a'

If you just want to convert a single runeto string, use a simple type conversion. runeis alias for int32, and converting integer numbers to string:

如果您只想将单个转换rune为string，请使用简单的类型转换。rune是 的别名int32，并将整数转换为string：

Converting a signed or unsigned integer value to a string type yields a string containing the UTF-8 representation of the integer.

将有符号或无符号整数值转换为字符串类型会生成一个包含整数的 UTF-8 表示的字符串。

So:

所以：

r := rune('a')
fmt.Println(r, string(r))

Outputs:

输出：

97 a

Also to loop over the runes of a stringvalue, you can simply use the for ... rangeconstruct:

同样要循环遍历string值的符文，您可以简单地使用for ... range构造：

for i, r := range "abc" {
    fmt.Printf("%d - %c (%v)\n", i, r, r)
}

Output:

输出：

0 - a (97)
1 - b (98)
2 - c (99)

Or you can simply convert a stringvalue to []rune:

或者您可以简单地将string值转换为[]rune：

fmt.Println([]rune("abc")) // Output: [97 98 99]

There is also utf8.DecodeRuneInString().

还有utf8.DecodeRuneInString()。

Try the examples on the Go Playground.

试试Go Playground上的例子。

Note:

笔记：

Your original code (using Scanner.Scan()) works like this:

您的原始代码（使用Scanner.Scan()）的工作方式如下：

1. You called Scanner.Init()which sets the Mode (b.Mode) to scanner.GoTokens.

2. Calling Scanner.Scan()on the input (from "a") returns scanner.Identbecause "a"is a valid Go identifier:

   c := b.Scan()
   if c == scanner.Ident {
       fmt.Println("Identifier:", b.TokenText())
   }
   
   // Output: "Identifier: a"
   

1. 您调用Scanner.Init()which 将 Mode ( b.Mode) 设置为scanner.GoTokens。

2. 调用Scanner.Scan()输入 (from "a") 会返回，scanner.Ident因为它"a"是一个有效的 Go 标识符：

   c := b.Scan()
   if c == scanner.Ident {
       fmt.Println("Identifier:", b.TokenText())
   }
   
   // Output: "Identifier: a"
   

回答by MarkJL

I know I'm a bit late to the party but here's a []rune to string function:

我知道我参加聚会有点晚了，但这里有一个 []rune to string 函数：

func runesToString(runes []rune) (outString string) {
    // don't need index so _
    for _, v := range runes {
        outString += string(v)
    }
    return
}

yes, there is a named return but I think it's ok in this case as it reduces the number of lines and the function is only short

是的，有一个命名返回，但我认为在这种情况下可以，因为它减少了行数并且函数很短