Splitting string into words length-based lists c#

Question

I have a string of words separated by spaces. How to split the string into lists of words based on the words length?

Example

inpu

Answer 1

You can use Where to find elements that match a predicate (in this case, having the correct length):

string[] words = input.Split();

List twos = words.Where(s => s.Length == 2).ToList();
List threes = words.Where(s => s.Length == 3).ToList();
List fours = words.Where(s => s.Length == 4).ToList();

Alternatively you could use GroupBy to find all the groups at once:

var groups = words.GroupBy(s => s.Length);

You can also use ToLookup so that you can easily index to find all the words of a specific length:

var lookup = words.ToLookup(s => s.Length);
foreach (var word in lookup[3])
{
    Console.WriteLine(word);
}

Result:

aaa
bbb
ccc

See it working online: ideone

---

In your update it looks like you want to remove the empty strings and duplicated words. You can do the former by using StringSplitOptions.RemoveEmptyEntries and the latter by using Distinct.

var words = input.Split((char[])null, StringSplitOptions.RemoveEmptyEntries)
                 .Distinct();
var lookup = words.ToLookup(s => s.Length);

Output:

aa, bb, cc
aaa, bbb, ccc
aaaa, bbbb, cccc

See it working online: ideone