“未知的转义序列"Go 中的错误 [英] "Unknown escape sequence" error in Go
问题描述
我有以下用 Go 编写的函数.这个想法是函数有一个字符串传递给它并返回找到的第一个 IPv4 IP 地址.如果没有找到 IP 地址，则返回一个空字符串.
I have the following function written in Go. The idea is the function has a string passed to it and returns the first IPv4 IP address found. If no IP address is found, an empty string is returned.
func parseIp(checkIpBody string) string {
reg, err := regexp.Compile("[0-9]+.[0-9]+.[0-9]+.[0-9]+")
if err == nil {
return ""
}
return reg.FindString(checkIpBody)
}
我得到的编译时错误是
未知的转义序列:.
我如何告诉 Go '.' 是我正在寻找的实际字符?我认为逃避它会成功，但显然我错了.
How can I tell Go that the '.' is the actual character I'm looking for? I thought escaping it would do the trick, but apparently I'm wrong.
推荐答案
反斜杠不会被正则表达式解析器解释，而是在字符串文字中被解释.你应该再次转义反斜杠:
The backslash isn't being interpreted by the regex parser, it's being interpreted in the string literal. You should escape the backslash again:
regexp.Compile("[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+")
用"双引号字符引用的字符串被称为解释的字符串文字"；在去.解释的字符串字面量类似于大多数语言中的字符串字面量: 反斜杠字符不按字面包含，它们用于为下一个字符赋予特殊含义.源必须在一行中包含 \ 两个反斜杠才能在解析的值中获得一个反斜杠字符.
A string quoted with " double-quote characters is known as an "interpreted string literal" in Go. Interpreted string literals are like string literals in most languages: backslash characters aren't included literally, they're used to give special meaning to the next character. The source must include \ two backslashes in a row to obtain an a single backslash character in the parsed value.
Go 有另一种替代方法，在为正则表达式编写字符串文字时非常有用:原始 字符串文字"；由 ` 反引号字符引用.原始字符串文字中没有特殊字符，因此只要您的模式不包含反引号，您就可以使用此语法而无需转义任何内容:
Go has another alternative which can be useful when writing string literals for regular expressions: a "raw string literal" is quoted by ` backtick characters. There are no special characters in a raw string literal, so as long as your pattern doesn't include a backtick you can use this syntax without escaping anything:
regexp.Compile(`[0-9]+.[0-9]+.[0-9]+.[0-9]+`)
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