字符串测试= @只是借此一线
甚至还出现在这里
多一些
线; 

匹配M = Regex.Match（测试，^（*）。，RegexOptions.Multiline）; 
如果（m.Success）
 Console.Write（m.Groups [0] .value的）; 
 

。往往被吹捧为匹配任何字符，虽然这是不完全正确。 。只匹配，如果你使用 RegexOptions.Singleline 选项的任何字符。如果没有这个选项，它匹配任何字符，除了'\\\
（行尾）。

这就是说，一个更好的选择可能是：

 字符串测试= @只是把这个第一行
还送有
多一些
线在这里; 

串firstLine中= test.Split（新的String [] {} Environment.NewLine，StringSplitOptions.None）[0]; 
 

击>
和更好的，是布赖恩拉斯穆森的版本：

 字符串FIRSTLINE = test.Substring（0，test.IndexOf（Environment.NewLine））; 
 

How can I get only the first line of multiline text using regular expressions?

        string test = @"just take this first line
        even there is 
        some more
        lines here";

        Match m = Regex.Match(test, "^", RegexOptions.Multiline);
        if (m.Success)
            Console.Write(m.Groups[0].Value);

string test = @"just take this first line
even there is 
some more
lines here";

Match m = Regex.Match(test, "^(.*)", RegexOptions.Multiline);
if (m.Success)
    Console.Write(m.Groups[0].Value);

. is often touted to match any character, while this isn't totally true. . matches any character only if you use the RegexOptions.Singleline option. Without this option, it matches any character except for '\n' (end of line).

That said, a better option is likely to be:

string test = @"just take this first line
even there is 
some more
lines here";

string firstLine = test.Split(new string[] {Environment.NewLine}, StringSplitOptions.None)[0];

And better yet, is Brian Rasmussen's version:

string firstline = test.Substring(0, test.IndexOf(Environment.NewLine));