C# 解析 "*" - 量词 {x,y}
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parsing "*" - Quantifier {x,y} following nothing
提问by loviji
fails when I try Regex.Replace()method.
how can i fix it?
当我尝试Regex.Replace()方法时失败。我该如何解决？
Replace.Method (String, String, MatchEvaluator, RegexOptions)
I try code
我试试代码
<%# Regex.Replace( (Model.Text ?? "").ToString(), patternText, "<b>" + patternText + "</b>", RegexOptions.IgnoreCase | RegexOptions.Multiline)%>
采纳答案by Joey
Did you try using only the string "*"as a regular expression? At least that's what causes your error here:
您是否尝试仅使用字符串"*"作为正则表达式？至少这就是导致您出现错误的原因：
PS Home:\> "a" -match "*"
The '-match' operator failed: parsing "*" - Quantifier {x,y} following nothing..
At line:1 char:11
+ "a" -match <<<< "*"
The character *is special in regular expressions as it allows the precedingtoken to appear zero or more times. But there actually has to be something preceding it.
该字符*在正则表达式中很特殊，因为它允许前面的标记出现零次或多次。但实际上必须有一些东西在它之前。
If you want to match a literal asterisk, then use \*as regular expression. Otherwise you need to specify whatmay get repeated. For example the regex a*matches either nothing or arbitrary many as in a row.
如果要匹配文字星号，请\*用作正则表达式。否则，你需要指定哪些可能会重复。例如，正则表达式在一行a*中要么不匹配任何匹配，要么匹配任意多个a。
回答by Hans Ke?ing
You appear to have a lone "*"in your regex. That is not correct. A "*"does not mean "anything" (like in a file spec), but "the previous can be repeated 0 or more times".
您"*"的正则表达式中似乎只有一个。那是不正确的。A"*"并不意味着“任何东西”（就像在文件规范中一样），而是“前一个可以重复 0 次或更多次”。
If you want "anything" you have to write ".*". The "."means "any single character", which will then be repeated.
如果你想要“任何东西”，你必须写".*". 的"."装置“的任何单个字符”，那么这将被重复。
Edit:
The same would happen if you use other quantifiers by their own: "+", "?"or "{n,m}"(where n and m are numbers that specify lower and upper limit).
编辑：如果您自己使用其他量词，也会发生同样的情况："+"，"?"或"{n,m}"（其中 n 和 m 是指定下限和上限的数字）。
- "*" is identical to "{0,}",
- "+" is identical to "{1,}",
- "?" is identical to "{0,1}"
- “*”与“{0,}”相同，
- "+" 与 "{1,}" 相同，
- “？” 与“{0,1}”相同
which might explain the text or the error message you get.
这可能会解释您收到的文本或错误消息。
回答by loviji
thanks,
谢谢，
and I fixed like this
我是这样固定的
<%# Regex.Replace( (Model.Text ?? "").ToString(), Regex.Escape(patternText), "<b>" + patternText + "</b>", RegexOptions.IgnoreCase | RegexOptions.Multiline)%>
