Question

How to select only unique values from a list in C#

Answer 1

using System;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static void Main() {
        List<int> list = new List<int> { 3, 5, 2, 1, 3, 3, 2, 8, 9, 5 };
        
        List<int> unique = list.Distinct().ToList();
        
        Console.WriteLine(string.Join(", ", unique));   
    }
}




/*
run:

3, 5, 2, 1, 8, 9

*/

 

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Answer 2

using System;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static void Main() {
        List<int> list = new List<int> { 3, 5, 2, 1, 3, 3, 2, 8, 9, 5 };
        
        List<int> unique = new HashSet<int>(list).ToList();
        
        Console.WriteLine(string.Join(", ", unique));   
    }
}




/*
run:

3, 5, 2, 1, 8, 9

*/

 

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Answer 3

using System;
using System.Collections.Generic;

class Program
{
    static void Main() {
        List<int> list = new List<int> { 3, 5, 2, 1, 3, 3, 2, 8, 9, 5 };
        
        var unique = new List<int>();
        
        foreach (var value in list) {
            if (!unique.Contains(value)) {
                unique.Add(value);
            }
        }
        
        Console.WriteLine(string.Join(", ", unique));   
    }
}




/*
run:

3, 5, 2, 1, 8, 9

*/

 

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