Drop the last item with LINQ [duplicate]

Question

Seems like a trivial task with LINQ (and probably it is), but I cannot figure out how to drop the last item of squence with LINQ. Using Take and passing the length of the sequence - 1 works fine of course. However, that approach seems quite inconvienient when chaining up multiple LINQ in a single line of code.

IEnumerable<T> someList ....  // this works fine var result = someList.Take(someList.Count() - 1);   // but what if I'm chaining LINQ ? var result = someList.Where(...).DropLast().Select(...)......;  // Will I have to break this up? var temp = someList.Where(...); var result = temp.Take(temp.Count() - 1).Select(...)........; 

In Python, I could just do seq[0:-1]. I tried passing -1 to Take method, but it does not seem to do what I need.

Answer 1

For .NET Core 2+ and .NET Standard 2.1 (planned), you can use .SkipLast(1).

For other platforms, you could write your own LINQ query operator (that is, an extension method on IEnumerable<T>), for example:

static IEnumerable<T> SkipLast<T>(this IEnumerable<T> source) {     using (var e = source.GetEnumerator())     {         if (e.MoveNext())         {             for (var value = e.Current; e.MoveNext(); value = e.Current)             {                 yield return value;             }         }     } } 

Unlike other approaches such as xs.Take(xs.Count() - 1), the above will process a sequence only once.

Answer 2

someList.Reverse().Skip(1).Reverse()