using System;

public class Program

{

    // For http://stackoverflow.com/questions/642125/encoding-xpath-expressions-with-both-single-and-double-quotes/38254661#38254661

    public static void Main()

    {

        Console.WriteLine(XpathExpression("Pizza Shed"));

        Console.WriteLine(XpathExpression("Bob's pizza"));

        Console.WriteLine(XpathExpression("\"Pizza\" Pam"));

        Console.WriteLine(XpathExpression("Fred's \"Fancy Pizza\""));

        Console.WriteLine(XpathExpression("Fred's \"Fancy Pizza\" and chik'fri"));      

    }

    public static string XpathExpression(string value)

    {

        if (!value.Contains("'"))

            return '\'' + value + '\'';

        else if (!value.Contains("\""))

            return '"' + value + '"';

        else

            return "concat('" + value.Replace("'", "',\"'\",'") + "')";

    }

}