Why are the data not sorted?

Question

Hi

With this code, i get first Bob, then Bill. So it doesn't sort the data. I found the solution (see below) but i want to know where is the error here, why it doesn't work.

Thanks

V

using System;
using System.Collections.Generic;
using System.Linq;
class MyClass
{
public string Naam;
public int Age; publuc string Country; }

List<MyClass> t = new List<MyClass>();

t.Add(new MyClass() { Name = "Bob", Age = 36, Cuntry = "UK" });

t.Add(new MyClass() { Name = "Bill", Age = 32, Country = "USA" });

.OrderBy(x => x.Age);
foreach (MyClass x in t)

Console.Write(x.Name + " " + x.Country + ", " + x.Age);

But with this code, it works:

var sort1 = t.OrderBy(x => x.Age);
foreach (var x in sort1)
Console.Write(x.Name + " " + x.Age;

Vishal Yelve · Answer

you need to add .ToList(); var result = t.OrderBy(x => x.Age).ToList(); foreach (MyClass x in result) Console.Write(x.Name + " " + x.Country + ", " + x.Age);

Vishal Joshi · Answer

Data does not get sorted because it requires an assignment. as in your other code it gets sorted because you applied an assignment. Below code wan't work because it's not having assignment. listObject.OrderBy(x => x.Age); Below is Code work because it has an assignment. var sortedListObject = listObject.OrderBy(x => x.Age); In your case you can directly use like below: foreach (var x in sort1.OrderBy(x => x.Age)) Console.Write(x.Name + " " + x.Age; The reason it requires assignment is, it's reading value from list and on same list it can't update simalteniously. for that it need another variable in which it can write.

Valerie Meunier · Answer

Thanks

Vishal Joshi · Answer

In this case, there is no use of .ToList() because it's already listed. if we try to fetch data from a database like SQL, in that case, it's IQuerialbe data and we need to use it.ToList() to get data in system memory. Also you can use .Sort() method like below to sort data without assignment. t.Sort((x,y) => x.Age.CompareTo(y.Age)); OrderBy(x => x.Age) will just caculate order by but not change the actual data, This is linq method. To change need to assign to self or to diffrent variable.

Valerie Meunier · Answer

Hi, thanks. It works also without ToList(), so what's the use of that? Further, what does this code do then if it doesn't order anything? OrderBy(x => x.Age); In this example, it works without assignment: why? List Fruit = new List { "apple", "pear", "banana" }; Fruit.Sort(); foreach (string f in Fruit) Console.Write(f + " "); But of course, it's another type ... Thanks again