using System;
using System.Text.RegularExpressions;
public class Test
{
public static void Main()
{
var s = "hello 'world' hehe";
var m = Regex.Match(s, "'([^']*)'");
string res = null;
if (m.Success) {
res = m.Groups[1].ToString();
}
Console.WriteLine(res);
}
}
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