Regex.Replace 不起作用

Question

I am having a strange issue with Regex.Replace

string test = "if the other party is in material breach of such contract and, after <span style=\"background-color:#ffff00;\">forty-five (45)</span> calendar days notice of such breach";
string final = Regex.Replace(test, "forty-five (45)", "forty-five (46)", RegexOptions.IgnoreCase);

the "final" string still shows "forty-five (45)". Any idea why? I am assuming it has to do something with the tag. How do I fix this?

Thanks

Answer 1

Escape the parenthesis. Depending on the language, might require two back slashes.

string final = Regex.Replace(test, "forty-five \(45\)", "forty-five (46)", RegexOptions.IgnoreCase);

Basically, parenthesis are defined to mean something, and by escaping the characters, you are telling regex to use the parenthesis character, and not the meaning.

Better yet, why are you using a Regex to do this at all? Try just doing a normal string replacement .

string final = test.Replace("forty-five (45)", "forty-six (46)")

Answer 2

Parentheses are special in regular expressions. They delimit a group , to allow for things such as alternation. For example, the regular expression foo(bar|bat)baz matches:

• foo , followed by
• either bar OR bat , followed by
• baz

So, a regular expression like foo(bar) will never match the literal string foo(bar) . What it will match is the literal string foobar . Consequently, you need to escape the metacharacters. In C#, this should do you:

string final = Regex.Replace(test, @"forty-five \(45\)", "forty-five (46)", RegexOptions.IgnoreCase);

The @-quoted string helps avoid headaches from excessive backslashes. Without it, you'd have to write "forty-five \\(45\\)".

Answer 3

如果您无法转义括号，请将它们放在字符类中：

forty-five [(]45[)]