CODEWITHSUNDEEP
c#.net
Sameera
Sameera

Reputation: 419

Looping Observable Collection from the Last Item

foreach(var item in myObservalbleCollection)
{
    //samoe coding
}

Above code will loop the items in the observable class from the beginning. I want to loop the this object from the last Item

ex 9,8,7,6,5,4,3,2,1,0 instead of 1,2,3,4,5,6,7,8,9... Please give me a solution to do this in c#

Upvotes: 0

Views: 2496

Answers (2)

Martin Liversage
Martin Liversage

Reputation: 106826

Instead of using foreach you can use a for loop running from the end of the collection and to the start:

for (var i = myObservableCollection.Count - 1; i >= 0; i -= 1) {
  var item = myObservableCollection[i];
  // Process item
}

This is possible because ObservableCollection<T> implement IList<T> which provides both the count of the elements in the collection and indexed access to these elements in addition to the forward teration provided by IEnumerable<T> used by foreach. This is the most efficient solution.

You can also use LINQ Reverse which is available for any collection implementing IEnumerable<T>:

foreach (var item in myObservableCollection.Reverse()) {
  // Process item
}

This will actually copy all the elements in the collection to a new array before iterating them in reverse order. While less efficient than the first solution it should not matter in most cases.

Upvotes: 3

Sajeetharan
Sajeetharan

Reputation: 222582

You could reverse the observablecollection and do the loop

var myObservalbleCollection = new ObservableCollection<YourType>(collection.Reverse());    
foreach(var item in myObservalbleCollection)
{
    //some coding
}

Upvotes: 2

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