Why are the data not sorted?

Valerie Meunier

4y1kC#

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

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

List t = new List();

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;

5 Replies

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Vishal Yelve4y ago
Accepted 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);
+3
Valerie Meunier4y ago
Thanks
+1
Vishal Joshi4y ago
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.
+1
Valerie Meunier4y ago
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
+1
Vishal Joshi4y ago
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.
+2