CODEWITHSUNDEEP
.netc#-4.0
GPGVM
GPGVM

Reputation: 5619

List<T>.Sort not sorting alphabetically

I was posed this trivia question and thought it was rather simplistic. The person asked me to explain why this list didn't sort alphabetically. I thought it a trick question till I threw it into a little stub project and they were right...no trick it doesn't sort alphabetically. I Googled and everything I read said Sort() would work the way I expect. So edjumakate me geniuses. I obviously don't have the answer.

string str_animals = "hyena, cat, elephant, dog, iguana";
List<string> lst_animals = new List<string>(str_animals.Split(','));

lst_animals.Sort();

After the sort my list is: cat, dog, elephant, iguana, hyena???? Hyena & iguana are out of order?

MSDN says "This method uses Array.Sort, which uses the QuickSort algorithm. This implementation performs an unstable sort; that is, if two elements are equal, their order might not be preserved. In contrast, a stable sort preserves the order of elements that are equal" but hyena and iguana are not equal so I don't see that unstable sort would matter.

What am I missing?

Thank You

Upvotes: 0

Views: 123

Answers (3)

8192K
8192K

Reputation: 5280

Simply use 

List<string> lst_animals = new List<string>(str_animals.Split(", "));

The space in ",_" is important!

Like it's been pointed out by others only splitting by a comma will have the split string have a prefixed space. And a space comes before letters regarding sorting.

Upvotes: 0

Frederik Gheysels
Frederik Gheysels

Reputation: 56934

You're using Split, which splits the string into different strings. Hyena is the first one, and has no preceding space. The others all have a space in front, which affects your sorting.

therefore, you should remove the leading space by trimming the strings after you've splitted the original string.

var animals = str_animals.Split(',').Select (a => a.Trim());

Upvotes: 1

keyboardP
keyboardP

Reputation: 69362

You need to trim the values after splitting because the whitespace will throw off the sort (making hyena come after iguana since hyena does not start with a whitespace).

List<string> lst_animals = new List<string>(str_animals.Split(',').Select(x => x.Trim()));

Upvotes: 5

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