Comparing two lists using LINQ - asp.net

Question

If I have 2 lists of strings:
List<string> firstList = new List<string>("010", "111", "123");
List<string> secondList = new List<string>("010", "111", "999");
How can I compare each individual character in each item from the lists? Ex: Should compare "0" with "0", "1" with "1", "0" with "0" and so on. It appears that I can use SelectMany but I am stuck on how to do it
EDIT:
These lists should return true when compared with each other (as asterisk means any character and I am validating to ensure that each item is exactly 3 chars in length)
List<string> firstList = new List<string>("010", "111", "123");
List<string> secondList = new List<string>("010", "1*1", "***");

Answer 1

Updated with wildcards
class WildcardStringComparer : IEqualityComparer<string>
{
public bool Equals(string s1, string s2)
{
if (s1.Length != s2.Length) return false;
for (int i = 0; i < s1.Length; i++)
{
if (s1[i] != s2[i] && s1[i] != '*' && s2[i] != '*')
return false;
}
return true;
}
public int GetHashCode(string obj)
{
throw new NotImplementedException();
}
}
Results:
List<string> firstList = new List<string>{"010", "111", "999"};
List<string> secondList = new List<string>{"010", "111", "999"};
bool res = firstList.SequenceEqual(secondList, new WildcardStringComparer()); // True
and
List<string> firstList = new List<string>{"010", "111", "999"};
List<string> secondList = new List<string>{"010", "111", "*99"};
bool res = firstList.SequenceEqual(secondList, new WildcardStringComparer()); // True
and
List<string> firstList = new List<string>{"010", "111", "999"};
List<string> secondList = new List<string>{"010", "111", "199"};
bool res = firstList.SequenceEqual(secondList, new WildcardStringComparer()); // False

Answer 2

If you just want to compare for a matching character sequence between your lists:
bool sameCharacters = Enumerable.SequenceEqual(firstList.SelectMany(x => x),
secondList.SelectMany(x => x));
This would result in true, i.e. for the following two lists - their character sequences match ("010111123" for both), their individual string entries do not:
List<string> firstList = new List<string> {"010", "111", "123" };
List<string> secondList = new List<string> {"010", "11", "1123" };
Edit in response to comments:
For a wildcard match you could use Zip() and compare each character, return true if they match based on wildcard conditions, then just check that each element in the zipped sequence is true.
var isWildCardMatch = firstList.SelectMany(x => x).Zip(secondList.SelectMany( x => x),
(a,b) =>
{
if(a==b || a =='' || b == '')
return true;
return false;
}).All( x=> x);
Above approach crossed string entry boundaries, which would cause false matches - here a better approach:
bool isWildCardMatch = firstList.Zip(secondList, (x, y) =>
{
var matchWord = y.Select((c, i) => c == '*' ? x[i] : c);
return matchWord.SequenceEqual(x);
}).All(x => x);

Answer 3

Assuming you want to compare the first character of the first string in the first list to the first character of the first string of the second list, the second character of the first string in the first list to the second character of the first string in the second list, etc. I can think of two implementations.
The one I would start with:
var firstCharList = new List<char>();
var secondCharList = new List<char>();
firstList.foreach(s =>
{
foreach(char c in s)
{
firstCharList.Add(c);
}
});
secondList.foreach(s =>
{
foreach(char c in s)
{
secondCharList.Add(c);
}
});
for(int i = 0; i < firstCharList.Length; i++)
{
if(firstCharList[i] == secondCharList[i]) yield return i;
}
That would generate a list (or array, or whatever) of ints that correspond to indexes of which both strings had the same character.
The second would be something like:
firstList.foreach(s =>
{
var index = firstList.IndexOf(s);
var sPrime = secondList[index];
for(int i = 0; i < s.Length; i++)
{
if(s[i] == sPrime[i]) yield return s[i];
}
}
That one just returns any characters that are equal at the same indexes.