Order a List (C#) by many fields? [duplicate]
I want to order a List of objects in C# by many fields, not just by one. For example, let's suppose I have a class called X with two Attributes, A and B, and I have the following objects, in that order:
object1 => A = "a", B = "h"
object2 => A = "a", B = "c"
object3 => A = "b", B = "x"
object4 => A = "b", B = "b"
and I want to order the list by A attribute first, and when they are equals, by B element, so the order would be:
"a" "c"
"a" "h"
"b" "b"
"b" "x"
As far as I know, the OrderBy method order by one parameter.
Question: How can I order a C# List by more than one field?
Solution 1:
Use ThenBy
:
var orderedCustomers = Customer.OrderBy(c => c.LastName).ThenBy(c => c.FirstName)
See MSDN: http://msdn.microsoft.com/en-us/library/bb549422.aspx
Solution 2:
Yes, you can do it by specifying the comparison method. The advantage is the sorted object don't have to be IComparable
aListOfObjects.Sort((x, y) =>
{
int result = x.A.CompareTo(y.A);
return result != 0 ? result : x.B.CompareTo(y.B);
});
Solution 3:
Make your object something like
public class MyObject : IComparable
{
public string a;
public string b;
virtual public int CompareTo(object obj)
{
if (obj is MyObject)
{
var compareObj = (MyObject)obj;
if (this.a.CompareTo(compareObj.a) == 0)
{
// compare second value
return this.b.CompareTo(compareObj.b);
}
return this.a.CompareTo(compareObj.b);
}
else
{
throw new ArgumentException("Object is not a MyObject ");
}
}
}
also note that the returns for CompareTo :
http://msdn.microsoft.com/en-us/library/system.icomparable.compareto.aspx
Then, if you have a List of MyObject, call .Sort() ie
var objList = new List<MyObject>();
objList.Sort();