[英]Detecting “\” (backslash) using Regex
I have a C# Regex like 我有一个C#正则表达式
[\"\'\\/]+
that I want to use to evaluate and return error if certain special characters are found in a string. 如果在字符串中找到某些特殊字符,我想用它来评估并返回错误。
My test string is: 我的测试字符串是:
\test
I have a call to this method to validate the string: 我有一个对此方法的调用来验证字符串:
public static bool validateComments(string input, out string errorString)
{
errorString = null;
bool result;
result = !Regex.IsMatch(input, "[\"\'\\/]+"); // result is true if no match
// return an error if match
if (result == false)
errorString = "Comments cannot contain quotes (double or single) or slashes.";
return result;
}
However, I am unable to match the backslash. 但是,我无法匹配反斜杠。 I have tried several tools such as regexpal and a VS2012 extension that both seem to match this regex just fine, but the C# code itself won't. 我尝试了几种工具,例如regexpal和VS2012扩展,它们似乎都可以很好地匹配此regex,但是C#代码本身不行。 I do realize that C# is escaping the string as it is coming in from a Javascript Ajax call, so is there another way to match this string? 我确实意识到C#会将字符串从Javascript Ajax调用传入时转义,所以还有另一种匹配该字符串的方法吗?
It does match /test or 'test or "test, just not \\test 它确实匹配/ test或'test或“ test,但不匹配\\ test
The \\
is used even by Regex(es). \\
甚至被正则表达式使用。 Try "[\\"\\'\\\\\\\\/]+"
(so double escape the \\
) 尝试"[\\"\\'\\\\\\\\/]+"
(因此请对\\
两次转义)
Note that you could have @"[""'\\\\/]+
" and perhaps it would be more readable :-) (by using the @
the only character you have to escape is the "
, by the use of a second ""
) 请注意,您可能有@"[""'\\\\/]+
”,也许它会更易读:-)(通过使用@
,唯一必须转义的字符是"
,通过使用第二个""
)
You don't really need the +
, because in the end [...]
means "one of", and it's enough for you. 您实际上并不需要+
,因为最后[...]
意思是“其中之一”,对您来说就足够了。
Don't eat what you can't chew... Instead of regexes use 不要吃你无法咀嚼的东西...代替正则表达式使用
// result is true if no match
result = input.IndexOfAny(new[] { '"', '\'', '\\', '/' }) == -1;
I don't think anyone ever lost the work because he preferred IndexOf
instead of a regex :-) 我认为没有人会丢失工作,因为他更喜欢IndexOf
而不是正则表达式:-)
您可以通过使字符串像这样@
逐字地解决此问题:
result = !Regex.IsMatch(input, @"[\""\'\\/]+");
Since backslashes are used as escapes inside regex themselves, I find it best to use verbatim strings when working with the regex library: 由于反斜杠本身用作正则表达式内的转义符,因此我发现在使用正则表达式库时最好使用逐字字符串:
string input = @"\test";
bool result = !Regex.IsMatch(input, @"[""'\\]+");
// ^^
// You need to double the double-quotes when working with verbatim strings;
// All other characters, including backslashes, remain unchanged.
if (!result) {
Console.WriteLine("Comments cannot contain quotes (double or single) or slashes.");
}
The only issue with that is that you must double your double-quotes (which is ironically what you need to do in your case). 唯一的问题是您必须将双引号加倍(具有讽刺意味的是,这是您需要做的事情)。
For the trivial case, I am able to use regexhero.net for your test expression using the simple: 对于平凡的情况,我可以使用regexhero.net使用以下简单的测试表达式:
\\
to validate 验证
\test
The code generated by RegExHero: RegExHero生成的代码:
string strRegex = @"\\";
RegexOptions myRegexOptions = RegexOptions.IgnoreCase;
Regex myRegex = new Regex(strRegex, myRegexOptions);
string strTargetString = @"\test";
foreach (Match myMatch in myRegex.Matches(strTargetString))
{
if (myMatch.Success)
{
// Add your code here
}
}
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