英文:
regexp.FindSubmatch with hex character codes
问题
我无法在某些简单情况下使用regexp.FindSubmatch。例如，以下代码可以正常工作：
assigned := regexp.MustCompile(`\x7f`)
group := assigned.FindSubmatch([]byte{0x7f})
fmt.Println(group)
（在playground中打印的是[[127]]）
但是，如果我将字节更改为0x80，它就无法正常工作。为什么呢？
英文:
I cannot regexp.FindSubmatch in certain simple cases. For example, following code works properly:
assigned := regexp.MustCompile(`\x7f`)
group := assigned.FindSubmatch([]byte{0x7f})
fmt.Println(group)
(in playground it prints [[127]])
But if I change byte to 0x80 it does not work. Why?
答案1
得分: 2
根据包文档中的说明：
> 所有字符都是UTF-8编码的码点。
因此，正则表达式\x80不匹配字节值0x80，而是匹配字符U+0080的UTF-8表示。如果我们将测试程序更改为：
func main() {
assigned := regexp.MustCompile(`\x80`)
group := assigned.FindSubmatch([]byte{1, 2, 3, 0xc2, 0x80})
fmt.Println(group)
}
现在我们得到了一个匹配的两个字节序列[[194 128]]，表示该字符。
无法将regexp包切换到二进制模式，因此您需要将输入转换为有效的UTF-8，或者使用其他包来匹配您的数据。
英文:
As mentioned in the package documentation:
> All characters are UTF-8-encoded code points.
So the regular expression \x80 does not match the byte value 0x80, but rather the UTF-8 representation of the character U+0080. This is evident if we change your test program to:
func main() {
assigned := regexp.MustCompile(`\x80`)
group := assigned.FindSubmatch([]byte{1, 2, 3, 0xc2, 0x80})
fmt.Println(group)
}
We now get a match for the two byte sequence [[194 128]], which represents that character in question.
There is no way to switch the regexp package into a binary mode, so you will either need to convert your inputs to valid UTF-8, or use a different package to match your data.
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