c# - Grouping based on the order of data -

i have set of data in following format.

a b c b b c 

i want group data in such way result should grouped alphabet , should based on order. example above data output should be

a - 2 b - 1 - 1 c - 1 b - 2 c - 1 

create variables keep track of last letter , count. loop on letters , emit data whenever letter changes.

list<char> letters = new list<char>() { 'a', 'a', 'b', 'a', 'c', 'b', 'b', 'c' };  char last = letters.first(); int count = 1; foreach (char letter in letters.skip(1)) {     if (letter == last)     {         count++;     }     else     {         console.writeline(last + " - " + count);         last = letter;         count = 1;     } } console.writeline(last + " - " + count); 

the first character handled outside of loop setting last = letters.first(), foreach loop starts second character calling letters.skip(1).

the last console.writeline there handle final character block.