static void Main(string[] args)
{
//double[] arr = new double[] { 1.0, -2.0, 3.0, -3.0 };
////IEnumerable<double> res = from i in arr
//// where i < 0.0
//// select i;
////res = arr.Where(k => k < 0.0).Select(k => k);
//var res = from i in arr
// where i < 0.0
// select new { Id = i };
////foreach (double d in res)
////{
//// Console.WriteLine("{0} ", d);
////}
//Console.WriteLine("{0} ", res.ElementAt(0).Id);
//Person[] person = new Person[]
//{
// new Person { Name="Name1", Id=1 },
// new Person { Name="Name2", Id=2 },
// new Person { Name="Name3", Id=3 }
//};
//XNamespace ns = "tu-varna.bg";
//XDocument document = new XDocument(
// new XElement("Persons", new XComment("Same Person"), new XAttribute(XNamespace.Xmlns + "tu-varna", ns),
// new XElement("Person", new XAttribute("ID", person[0].Id), new XElement("Name", person[0].Name)),
// new XElement("Person", new XAttribute("ID", person[1].Id), new XElement("Name", person[1].Name)),
// new XElement("Person", new XAttribute("ID", person[2].Id), new XElement("Name", person[2].Name)))
// );
//document.Declaration = new XDeclaration("1.0", "UTF-8", "standalone");
//Console.WriteLine(document);
//document.Save("Persons.xtml");
//XElement element = new XElement("Name", "Ivan");
//XAttribute attribut = new XAttribute("Id", 1);
//Console.WriteLine(element);
//Console.WriteLine(attribut);
//Console.WriteLine((string) element);
//Console.WriteLine((int) attribut);
//XStreamingElement element0 = new XStreamingElement("Persons", new XComment("Same Person"), new XAttribute(XNamespace.Xmlns + "tu-varna", ns),
// from p in person
// select new XElement("Person", new XAttribute("Id", p.Id), new XElement("Name", p.Name)));
//person[0].Id = 5;
//XDocument document0 = new XDocument(element0);
//Console.WriteLine(document0);
//document.Save("Persons0.xtml");
//XDocument document1 = XDocument.Load("Persons0.xtml");
//var restord = from p in document1.Descendants("Person")
// select new Person { Id = (int) p.Attribute("Id"), Name = (string) p.Element("Name") };
//foreach (var p in restord)
//{
// Console.WriteLine("{0} {1}", p.Id, p.Name);
//}
Student[] student = new Student[] {
new Student {
fnum = 1, name = "S Name1"
},
new Student {
fnum = 2, name = "S Name2"
},
new Student {
fnum = 3, name = "S Name3"
},
new Student {
fnum = 4, name = "S Name4"
},
};
D[] d = new D[] {
new D {
number = 1, name = "D Name1"
},
new D {
number = 2, name = "D Name2"
},
new D {
number = 3, name = "D Name3"
},
new D {
number = 4, name = "D Name4"
},
};
O[] o = new O[] {
new O {
fnum = 1, number = 1, bal = 4
},
new O {
fnum = 2, number = 1, bal = 3
},
new O {
fnum = 3, number = 3, bal = 5
},
new O {
fnum = 2, number = 4, bal = 6
},
};
//1
Console.WriteLine(student.Where(s => s.fnum == o.Where(o1 => o1.bal == 6).FirstOrDefault().fnum).FirstOrDefault().name);
//2
o.Where(o1 => o1.bal == 6).Where(o2 => d.Any(d1 => d1.number == o2.number));
//3
Console.WriteLine(student.Where(s => s.fnum == o.Where(o1 => o1.bal == 6).FirstOrDefault().fnum).FirstOrDefault().name);
}