using System;
using System.Text.RegularExpressions;
public class Test
{
public static void Main()
{
String s = @"
hello 'world'
'foo' bar
'foo bar'
foo 'bar' but gar 'har'
";
String r = Regex.Replace(s, @"'([^']*)'", "'%$1%'");
Console.WriteLine(r);
}
}
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