用引号内的字符串将CSV行与分号和引号匹配 [英] Match CSV line with semicolons and quotation inside a quoted string

问题描述

我正在尝试解析单个csv文件.目前，它是通过一些在线正则表达式网页来完成的，但最终必须使用c#来实现.(作为评论中某些问题的反应)

Im trying to parse a single of a csv file. Curently it is done with some online regex webpage but in the end it has to be implemented in c#. (as reaction of some question in the comments)

我在SO上阅读了许多其他文章以自己弄清楚，但我坚持解决它.

I read a lot of other articels here on SO to figure it out by myself, but im stuck in solving it.

我的RegExp测试行如下所示(更新:引号内的引号转义):

My test line for my RegExp looks like this (UPDATE: quotes escaped inside of quoted-strings):

;;"test123; weiterer Text" ;;"Test mit" Zeichen im Spaltenwert;nächsteSpalte mit" Begrenzungszeichen;"4711"; irgendwas 123,4; 1222;"foo" test"

;;"test123;weiterer Text";;"Test mit "" Zeichen im Spaltenwert";nächste Spalte mit "" Begrenzungszeichen;"4711";irgendwas 123,4;1222;"foo""test"

• ; 是分隔符
• "是带引号的列的符号
• ; is the delimiter
• " is the sign for quoted columns

问题:

• 该行可能包含空列(分号后跟分号没有任何文字)
• 带引号的字符串可能包含引号，例如此处"Test mit"Zeichen im Spaltenwert"
• 列分隔符也可能出现在带引号的字符串中，例如:"test123; weiterer Text"

到目前为止，我通过多次谷歌搜索做了什么，而我对正则表达式的了解有限，就是这个表达式

What i have done so far with several googling and my limited understanding of regular expressions is this expression

(?< = ^ |;)(\.\" | [^;] *)| [^;] +

(?<=^|;)(\".\"|[^;]*)|[^;]+

这给出了以下结果

        [0] => 
        [1] => 
        [2] => "test123
        [3] => weiterer Text"
        [4] => 
        [5] => "Test mit " Zeichen im Spaltenwert"
        [6] => nächste Spalte mit " Begrenzungszeichen
        [7] => "4711"
        [8] => irgendwas 123,4
        [9] => 1222
        [10] => "foo"test"

经过测试 https://www.myregextester.com/

我现在遇到的问题是元素2和3.文本

The problem i have now is at the elements 2 and 3. This text

"test123;weiterer Text"

只能是一列，但会在带引号的字符串内以分号分隔，尽管我以为我告诉表达式要匹配引号内的所有内容.

has to be one column but gets splited at the semicolon inside of the quoted string, although i thought i told the expression to match everysthing inside of quotation marks.

我们非常感谢您的帮助.预先感谢.

Any help here is highly appreciated. Thanks in advance.

推荐答案

假设一个正确的csv使用双引号进行转义(" )，即可以逐行读取

Assuming a proper csv that uses doubled quotes for escaping (""), that is read line by line you can use

"(?:[^"]+|"")*"|[^;]+|(?<=;|^)(?=;|$)

基本上三种不同的方式来匹配列:

Basically three different ways to match a column:

• (?:[^"] + |")*"开头和结尾的引号之间用非引号或双引号
• [^;] + 一系列非semikolons
• (?< =; | ^)(?=; | $)分号之间或分号与开始/结束之间的空字段
• "(?:[^"]+|"")*" starting and closing quote with non-quotes or double quotes between
• [^;]+ a series of non-semikolons
• (?<=;|^)(?=;|$) an empty field between semikolons or between semikolon and start/end

注意:

• 如果要在多行上下文中使用它，则必须在否定的字符类中添加 \ n
• 它不处理与引号字段连接的前导或尾随空格

请参见 https://regex101.com/r/twKZVN/1

(尽管regex 101测试PCRE模式，但所有使用的功能也都可以在.net模式中使用.

(While regex 101 tests a PCRE pattern, all features used are also available in a .net pattern.

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