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Get count of unique characters between first and last letter

I'm trying to get the unique characters count that are between the first and last letter of a word. For example: if I type Yellow the expected output is Y3w, if I type People the output should be P4e and if I type Money the output should be M3y. This is what I tried:
//var strArr = wordToConvert.Split(' ');
string[] strArr = new[] { "Money","Yellow", "People" };
List<string> newsentence = new List<string>();
foreach (string word in strArr)
{
if (word.Length > 2)
{
//ignore 2-letter words
string newword = null;
int distinctCount = 0;
int k = word.Length;
int samecharcount = 0;
int count = 0;
for (int i = 1; i < k - 2; i++)
{
if (word.ElementAt(i) != word.ElementAt(i + 1))
{
count++;
}
else
{
samecharcount++;
}
}
distinctCount = count + samecharcount;
char frst = word[0];
char last = word[word.Length - 1];
newword = String.Concat(frst, distinctCount.ToString(), last);
newsentence.Add(newword);
}
else
{
newsentence.Add(word);
}
}
var result = String.Join(" ", newsentence.ToArray());
Console.WriteLine("Output: " + result);
Console.WriteLine("----------------------------------------------------");
With this code I'm getting the expect output for Yellow, but seems that is not working with People and Money. What can I do to fix this issue or also I'm wondering is maybe there is a better way to do this for example using LINQ/Regex.

Here's an implementation that uses Linq:
string[] strArr = new[]{"Money", "Yellow", "People"};
List<string> newsentence = new List<string>();
foreach (string word in strArr)
{
if (word.Length > 2)
{
// we want the first letter, the last letter, and the distinct count of everything in between
var first = word.First();
var last = word.Last();
var others = word.Skip(1).Take(word.Length - 2);
// Case sensitive
var distinct = others.Distinct();
// Case insensitive
// var distinct = others.Select(c => char.ToLowerInvariant(c)).Distinct();
string newword = first + distinct.Count().ToString() + last;
newsentence.Add(newword);
}
else
{
newsentence.Add(word);
}
}
var result = String.Join(" ", newsentence.ToArray());
Console.WriteLine(result);
Output:
M3y Y3w P4e
Note that this doesn't take account of case, so the output for FiIsSh is 4.

Maybe not the most performant, but here is another example using linq:
var words = new[] { "Money","Yellow", "People" };
var transformedWords = words.Select(Transform);
var sentence = String.Join(' ', transformedWords);
public string Transform(string input)
{
if (input.Length < 3)
{
return input;
}
var count = input.Skip(1).SkipLast(1).Distinct().Count();
return $"{input[0]}{count}{input[^1]}";
}

You can implement it with the help of Linq. e.g. (C# 8+)
private static string EncodeWord(string value) => value.Length <= 2
? value
: $"{value[0]}{value.Substring(1, value.Length - 2).Distinct().Count()}{value[^1]}";
Demo:
string[] tests = new string[] {
"Money","Yellow", "People"
};
var report = string.Join(Environment.NewLine, tests
.Select(test => $"{test} :: {EncodeWord(test)}"));
Console.Write(report);
Outcome:
Money :: M3y
Yellow :: Y3w
People :: P4e

A lot of people have put up some good solutions. I have two solutions for you: one uses LINQ and the other does not.
LINQ, Probably not much different from others
if (str.Length < 3) return str;
var midStr = str.Substring(1, str.Length - 2);
var midCount = midStr.Distinct().Count();
return string.Concat(str[0], midCount, str[str.Length - 1]);
Non-LINQ
if (str.Length < 3) return str;
var uniqueLetters = new Dictionary<char, int>();
var midStr = str.Substring(1, str.Length - 2);
foreach (var c in midStr)
{
if (!uniqueLetters.ContainsKey(c))
{
uniqueLetters.Add(c, 0);
}
}
var midCount = uniqueLetters.Keys.Count();
return string.Concat(str[0], midCount, str[str.Length - 1]);
I tested this with the following 6 strings:
Yellow
Money
Purple
Me
You
Hiiiiiiiii
Output:
LINQ: Y3w, Non-LINQ: Y3w
LINQ: M3y, Non-LINQ: M3y
LINQ: P4e, Non-LINQ: P4e
LINQ: Me, Non-LINQ: Me
LINQ: Y1u, Non-LINQ: Y1u
LINQ: H1i, Non-LINQ: H1i
Fiddle
Performance-wise I'd guess they're pretty much the same, if not identical, but I haven't run any real perf test on the two approaches. I can't imagine they'd be much different, if at all. The only real difference is that the second route expands Distinct() into what it probably does under the covers anyway (I haven't looked at the source to see if that's true, but that's a pretty common way to get a count of . And the first route is certainly less code.

I Would use Linq for that purpose:
string[] words = new string[] { "Yellow" , "People", "Money", "Sh" }; // Sh for 2 letter words (or u can insert 0 and then remove the trinary operator)
foreach (string word in words)
{
int uniqeCharsInBetween = word.Substring(1, word.Length - 2).ToCharArray().Distinct().Count();
string result = word[0] + (uniqeCharsInBetween == 0 ? string.Empty : uniqeCharsInBetween.ToString()) + word[word.Length - 1];
Console.WriteLine(result);
}

Split and then Joining the String step by step - C# Linq

Here is my string:
www.stackoverflow.com/questions/ask/user/end
I split it with / into a list of separated words:myString.Split('/').ToList()
Output:
www.stackoverflow.com
questions
ask
user
end
and I need to rejoin the string to get a list like this:
www.stackoverflow.com
www.stackoverflow.com/questions
www.stackoverflow.com/questions/ask
www.stackoverflow.com/questions/ask/user
www.stackoverflow.com/questions/ask/user/end
I think about linq aggregate but it seems it is not suitable here. I want to do this all through linq

You can try iterating over it with foreach
var splitted = "www.stackoverflow.com/questions/ask/user/end".Split('/').ToList();
string full = "";
foreach (var part in splitted)
{
full=$"{full}/{part}"
Console.Write(full);
}
Or use linq:
var splitted = "www.stackoverflow.com/questions/ask/user/end".Split('/').ToList();
var list = splitted.Select((x, i) => string.Join("/", a.Take(i + 1)));

Linq with side effect:
string prior = null;
var result = "www.stackoverflow.com/questions/ask/user/end"
.Split('/')
.Select(item => prior == null
? prior = item
: prior += "/" + item)
.ToList();
Let's print it out
Console.WriteLine(string.Join(Environment.NewLine, result));
Outcome:
www.stackoverflow.com
www.stackoverflow.com/questions
www.stackoverflow.com/questions/ask
www.stackoverflow.com/questions/ask/user
www.stackoverflow.com/questions/ask/user/end

Linq without side effects ;)
Enumerable.Aggregate can be used here if we use List<T> as a result.
var raw = "www.stackoverflow.com/questions/ask/user/end";
var actual =
raw.Split('/')
.Aggregate(new List<string>(),
(list, word) =>
{
var combined = list.Any() ? $"{list.Last()}/{word}" : word;
list.Add(combined);
return list;
});

without Linq write below code,
var str = "www.stackoverflow.com/questions/ask/user/end";
string[] full = str.Split('/');
string Result = string.Empty;
for (int i = 0; i < full.Length; i++)
{
Console.WriteLine(full[i]);
}
for (int i = 0; i < full.Length; i++)
{
if (i == 0)
{
Result = full[i];
}
else
{
Result += "/" + full[i];
}
Console.WriteLine(Result);
}

Join List of strings trailing values don't require delimiters if the right most value is null

What im trying to achieve, but cant get my head around is if i have a list of strings say:
{"test","","data","","123","44"}
this should be joined by a character:
test::data::123:44
but if the list at the end is empty dont delimiter it
{"test","","data","","",""}
should be:
test::data
{"test","","","","",""}
should be:
test
{"test","","","","","44"}
should be:
test::::44
however the list can be of varying lengths which adds another level of complexity.

Just exclude the trailing empty elements from the list Count and then Join the remaining using Take:
List<string> input = ...;
int count = input.Count;
while (count > 0 && string.IsNullOrEmpty(input[count - 1]))
count--;
var output = string.Join(":", input.Take(count));
Using the List<T> specific FindLastIndex method, it can be reduced to the following "one liner":
var output = string.Join(":",
input.Take(input.FindLastIndex(s => !string.IsNullOrEmpty(s)) + 1));

First, with your array:
test = test.Where(x => !string.IsNullOrEmpty(x)).ToArray();
where "test" is your array.
then:
string.Join("::", test);
EDIT:
If you're getting your array of strings by splitting another string, consider the following:
string[] strs = myString.split(someDelimeter, StringSplitOptions.RemoveEmptyEntries);

Start by identifying the last element you want, then slice your list and join as you normally would:
var lastElementIndex = strings.Select((s, index) => string.IsNullOrEmpty(s) ? -1 : index).Max();
var prefix = strings.Take(lastElementIndex + 1);
var result = string.Join(":", prefix);

var obj = {"test","","data","","123","44"};
var count = obj.Count;
for (var i = count - 1; i > -1; i--)
{
if (obj[i]==String.Empty) {
obj.RemoveAt(i);
}
else break;
}
var arr = obj.Split(new char[] { ','}, StringSplitOptions.RemoveEmptyEntries);
var output = arr.Join(":", arr);

I want substring from set of string after a pattern exist in c#

I have 3 string ---
m60_CLDdet2_LOSS2CLF_060520469434_R0RKE_52_GU
m60_CLDdet2_LOSS2CLF_060520469434_R10KE_52_TCRER
m60_CLDdet2_LOSS2CLF_060520469434_R0HKE_52_NT
and I want R0RKE_52_GU, R10KE_52_TCRER,R0HKE_52_NT.
Note: m60_CLDdet2_LOSS2CLF_060520469434 is varying so I want to find substring if R0RKE or R10KE or R0HKE exists

I would suggest using a Regular expression for this, it is much more versatile for pattern matching.
var matches = System.Text.RegularExpressions.Regex.Matches(text, #"(R0RKE|R10KE|R0HKE).*");

I want to find substring if R0RKE or R10KE or R0HKE exists
This LINQ query returns the desired result:
var strings=new[]{"m60_CLDdet2_LOSS2CLF_060520469434_R0RKE_52_GU","m60_CLDdet2_LOSS2CLF_060520469434_R10KE_52_TCRER","m60_CLDdet2_LOSS2CLF_060520469434_R0HKE_52_NT"};
string[] starts = { "R0RKE", "R10KE", "R0HKE" };
var result = strings
.Select(str => new { str, match = starts.FirstOrDefault(s => str.IndexOf("_" + s) >= 0)})
.Where(x => x.match != null)
.Select(x => x.str.Substring(x.str.IndexOf(x.match)));
Console.Write(String.Join(",", result)); // R0RKE_52_GU,R10KE_52_TCRER,R0HKE_52_NT

I write it into static method:
private static string TakeIt(string inputString)
{
if (!Regex.IsMatch(inputString, "(R0RKE|R10KE|R0HKE)"))
{
return string.Empty;
}
var regex = new Regex(#"_");
var occurances = regex.Matches(inputString);
var index = occurances[3].Index + 1;
return inputString.Substring(index, inputString.Length - index);
}
void Main()
{
var string1 = "m60_CLDdet2_LOSS2CLF_060520469434_R0RKE_52_GU";
var string2 = "m60_CLDdet2_LOSS2CLF_060520469434_R10KE_52_TCRER";
var string3 = "m60_CLDdet2_LOSS2CLF_060520469434_R0HKE_52_NT";
var string4 = "m60_CLDdet2_LOSS2CLF_060520469434_hhhhh";
Console.WriteLine(TakeIt(string1));
Console.WriteLine(TakeIt(string2));
Console.WriteLine(TakeIt(string3));
Console.WriteLine(TakeIt(string4));
}
Hope this help.

Update: added .Any - it simplifies the code and it's just as same efficient.
If you just need to check for three strings inside string array you can do :
static string[] GetStrings(string[] dirty, string[] lookUpValues)
{
List<string> result = new List<string>();
for (int i = 0; i < dirty.Length; i++) if (lookUpValues.Any(dirty[i].Contains)) result.Add(dirty[i]);
return result.ToArray();
}
Usage: string[] result = GetStrings(dirty, new[] {"R0RKE", "R10KE", "R0HKE"});
Also you can use LINQ query and Regex.Matches as others advised.

Find a fixed length string with specific string part in C#

I want to find a string of fixed length with specific substring. But I need to do it like we can do in SQL queries.
Example:
I have strings like -
AB012345
AB12345
AB123456
AB1234567
AB98765
AB987654
I want to select strings that have AB at first and 6 characters afterwards. Which can be done in SQL by SELECT * FROM [table_name] WHERE [column_name] LIKE 'AB______' (6 underscores after AB).
So the result will be:
AB012345
AB123456
AB987654
I need to know if there is any way to select strings in such way with C#, by using AB______.

You can use Regular Expressions to filter the result:
List<string> sList = new List<string>(){"AB012345",
"AB12345",
"AB123456",
"AB1234567",
"AB98765",
"AB987654"};
var qry = sList.Where(s=>Regex.Match(s, #"^AB\d{6}$").Success);

Considering you have an string array:
string[] str = new string[3]{"AB012345", "A12345", "AB98765"};
var result = str.Where(x => x.StartsWith("AB") && x.Length == 8).ToList();
The logic is if it starts with AB, and its length is 8. It is your best match.

this should do it
List<string> sList = new List<string>(){
"AB012345",
"AB12345",
"AB123456",
"AB1234567",
"AB98765",
"AB987654"};
List<string> sREsult = sList.Where(x => x.Length == 8 && x.StartsWith("AB")).ToList();
first x.Length == 8 determines the length and x.StartsWith("AB") determines the required characters at the start of the string

This can be achieved by using string.Startwith and string.Length function like this:
public bool CheckStringValid (String input)
{
if (input.StartWith ("AB") && input.Length == 8)
{
return true;
}
else
{
return false;
}
}
This will return true if string matches your criteria.
Hope this helps.

var strlist = new List<string>()
{
"AB012345",
"AB12345",
"AB123456",
"AB1234567",
"AB98765",
"AB987654"
};
var result = strlist.Where(
s => (s.StartsWith("AB") &&(s.Length == 8))
);
foreach(var v in result)
{
Console.WriteLine(v.ToString());
}