Sorting C# List based on its element

Question

I have the C# class as follows :

public class ClassInfo {
    public string ClassName;
    public int BlocksCovered;
    public int BlocksNotCovered;


    public ClassInfo() {}

    public ClassInfo(string ClassName, int BlocksCovered, int BlocksNotCovered) 
    {
        this.ClassName = ClassName;
        this.BlocksCovered = BlocksCovered;
        this.BlocksNotCovered = BlocksNotCovered;
    }
}

And I have C# List of ClassInfo() as follows

List<ClassInfo> ClassInfoList;

How can I sort ClassInfoList based on BlocksCovered?

Carra · Accepted Answer · 2011-03-07 22:53:04Z

7

myList.Sort((x,y) => x.BlocksCovered.CompareTo(y.BlocksCovered)

answered Mar 7, 2011 at 22:53

Carra

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Comments

BrokenGlass · Accepted Answer · 2011-03-07 22:48:42Z

6

This returns a List<ClassInfo> ordered by BlocksCovered:

var results = ClassInfoList.OrderBy( x=>x.BlocksCovered).ToList();

Note that you should really make BlocksCovered a property, right now you have public fields.

answered Mar 7, 2011 at 22:48

BrokenGlass

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Comments

Steve Guidi · Accepted Answer · 2011-03-07 22:56:59Z

1

If you have a reference to the List<T> object, use the Sort() method provided by List<T> as follows.

ClassInfoList.Sort((x, y) => x.BlocksCovered.CompareTo(y.BlocksCovered));

If you use the OrderBy() Linq extension method, your list will be treated as an enumerator, meaning it will be redundantly converted to a List<T>, sorted and then returned as enumerator which needs to be converted to a List<T> again.

answered Mar 7, 2011 at 22:56

Steve Guidi

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2 Comments

Mark Sowul Over a year ago

FWIW, LINQ is usually smart enough to take advantage of underlying types, e.g. Count() will use ICollection<T>'s count property. I don't know about Sort() though.

BrokenGlass Over a year ago

+1 I agree in general, but on lists of "normal" size this is not an issue so I personally shoot for readability, and that's where the LINQ syntax is clearly better. Also the overall Big O doesn't change - sorting is O(n*log n), traversal is O(n).

neontapir · Accepted Answer · 2011-03-07 22:49:17Z

0

I'd use Linq, for example:

ClassInfoList.OrderBy(c => c.ClassName);

answered Mar 7, 2011 at 22:49

neontapir

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2 Comments

Yasmine GreenApple Over a year ago

the OrderBy doesn't affect the orginal list, it creates another list

neontapir Over a year ago

True, but why is that relevant? If you want to sort the list permanently, then save the results as a new list.

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