Conditions on foreach loop using Linq

Question

I have a List<KeyValuePair<string, Records> mylist;

I would like to loop in the list foreach different key value. Something like

foreach(var item in myList.select(/\*query the disctinct values of key here ?*/)

is it possible ? How ?

You can probably get a good footing by looking [here](http://stackoverflow.com/questions/998066/linq-distinct-values), for starters.. — gravity, Apr 26 '17 at 15:37
If you have a list of pairs that has duplicate keys, how will you determine which value to use for a key that has multiple values tied to it? Ex: `key: 1, value: "hello"`; `key: 1, value: "world"`. How do you pick between "hello" and "world" since they have the same key? — Blake Thingstad, Apr 26 '17 at 15:48
I may have poorly explain my needs. I will reuse your comment exemple to help me. I need something like serialize/display/process together all elements with key = 1, then serialize/display/process together all element with key = 2, etc... — Ythio Csi, Apr 27 '17 at 08:47

Nikhil Agrawal · Accepted Answer · 2017-04-26T15:44:41.520

4

You can do

foreach(var item in myList.Select(x => x.Key).Distinct())
{
    //Your Logic
}

myList.Select(x => x.Key).Distinct() would give you distinct Keys and foreach will loop over them.

edited Apr 26 '17 at 15:44

answered Apr 26 '17 at 15:36

Nikhil Agrawal

That seems exactly what i need. I have an error though, `Cannot convert lambda expression to type 'System.Collections.Generic.IEqualityComparer>' ` – Ythio Csi Apr 26 '17 at 15:43
Will it loop every element in myList ? Or just once per distinct key ? – Ythio Csi Apr 27 '17 at 08:50
`myList.Select(x => x.Key)` will have all keys, irrespective of occurrence. `Distinct` will do the distinct. – Nikhil Agrawal Apr 27 '17 at 08:56

1 Answers1