C＃RegEx匹配第二行中的所有内容

Question

I need a regex to match all in the second line.

First Line
Second Line

I have tried using \\n(.*)\\n but it returns the empty value.

Match match in Regex.Matches(line, @"\n(.*)\n", RegexOptions.Multiline)

Answer 1

You don't need regex for that. Just split input string on lines and get line which you need:

var line= @"First Line
Second Line";

var secondLine = line.Split('\n')[1]; // "Second Line"

You can also check count of lines in your string before getting required line by index to avoid IndexOutOfRange exception.

Even with regex it's better to use Split method if you are going to split input by some value (but again, it's an overkill if you are simply splitting by lines without some pattern):

 var secondLine = Regex.Split(line, Environment.NewLine)[1];

Answer 2

You're trying to match two end of line while the your input only have one.

Change to \\n(.*)

Answer 3

With the RegexOptions.MultiLine enabled, you can use the following:

\n^(.*)$

When Multiline is enabled, ^ and $ will match the beginning and the end of a line instead of the beginning and end of a string.

Example: Regex101