仅捕获单个比赛-正则表达式

Question

i want to capture only the first match through the expression

<p>.*?</p>

i have tried <p>.*?</p>{1} but it is not working it returns all the p tags which are in the html document, please help

Answer 1

It looks like you are using a method which returns every match in the string given a regex, that being the case you need to anchor the regex to the beggining of the string so it doesn't return every match, but only the first one:

^.*?<p>.*?</p>

Use parentheses to capture what you want to capture.

PS: Here goes the standard 'avoid using regex to parse HTML, use a proper HTML parser' advice. This simple regex will fail for nested <p> sections (which I don't recall if are valid in HTML, but still you can probably get them even if they aren't).

Answer 2

The Regex.Match method does this by default, and the regular expression is correct.

Regex regex = new Regex("<p>(.*?)</p>");
Match match = regex.Match("<p>1</p><p>2</p>");
Console.WriteLine("{0}", match.Value);

Running this program will print 1 .