linq on two string array

[pkn.hegde]

string[] listOne = new string[] { "dog", "cat", "car", "apple"};
string[] listTwo = new string[] { "car", "apple"};

What I need is to order listOne by the order of items in listTwo (if present). So the new list would be in this order; "car", "apple", "dog", "cat"

[BioPhysEngr]

I don't know of a quick way to do it with Linq (probably because I don't use Linq terribly often, perhaps another member will know).

You can do it normally though, if you have a way to quickly test membership in both lists.

List<string> orderedResult = new List<string>();
for(int i = 0; i < listTwo.Length; i++)
    if( isMember(listTwo[i], listOne) )  //If the i'th item in list2 is contained in list1
        orderedResult.Add(listTwo[i]);

for(int i = 0; i < listOne.Length; i++)
    if( !isMember(listOne[i], listTwo) ) //If the i'th item in list1 is NOT contained in list2
        ordreredResult.Add(listOne[i]);

For short lists, it is probably sufficient to implement isMember as a loop. If you had longer lists, you'd probably want to construct a dictionary for each list:

Dictionary<string, int> listOneDict = new Dictionary<string, int>();
foreach(string s in listOne)
    listOneDict.Add(s, 0);

And then test for membership:

listOneDict.ContainsKey("someStringToTest");

All of these snippets assume that listOne and listTwo have no repeated elements.

Anyway, I think that ought to work, but I didn't explicitly test it. Push back if you need more information. Hope that is a little helpful!