Golang从符文转换为字符串 [英] Golang converting from rune to string

问题描述

我有以下代码，应该将 rune 转换为 string 并将其打印出来.但是，在打印时，我得到了未定义的字符.我无法找出错误所在:

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

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))
}

推荐答案

那是因为您使用了 Scanner.Scan() 读取 rune ，但它还有其他作用. Scanner.Scan()可用于读取由 Scanner.Mode 代币或 rune >位掩码，并以 text/scanner 的形式返回特殊常数.包，而不是读取的符文本身.

That's because you used Scanner.Scan() to read a rune but it does something else. Scanner.Scan() can be used to read tokens or runes of special tokens controlled by the Scanner.Mode bitmask, and it returns special constants form the text/scanner package, not the read rune itself.

要读取单个 rune ，请使用 Scanner.Next() 代替:

To read a single rune use Scanner.Next() instead:

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

输出:

97 a 'a'

如果您只想将单个 rune 转换为 string ，请使用简单类型转化. rune 是 int32 的别名，并将整数转换为 string :

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

将有符号或无符号整数值转换为字符串类型会产生一个包含整数的UTF-8表示形式的字符串.

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

所以:

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

输出:

97 a

还可以遍历 string 值的符文，您只需使用 for ... range 构造:

Also to loop over the runes of a string value, you can simply use the for ... range construct:

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

输出:

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

或者您可以简单地将 string 值转换为 [] rune :

Or you can simply convert a string value to []rune:

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

还有 utf8.DecodeRuneInString()

在转到游乐场上尝试示例.

注意:

您的原始代码(使用 Scanner.Scan())如下所示:

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

1. 您致电了 Scanner.Init() 将模式( b.Mode )设置为 scanner.GoTokens .

2. 在输入上调用 Scanner.Scan()(从"a" )返回 scanner.Ident ，因为"a" 是有效的Go标识符:

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.Ident because "a" is a valid Go identifier:

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

// Output: "Identifier: a"

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