Question

I will have a number which was taken as input from the use or i am storing a number assigned to a string as

  string s"1234567";

As for this the index of each string will be as 0,1,2,3,4 and so on

I would like to add the number with that index as 1+0, 2+1 , 3+2 and so on like that

so that the output should be 1,3,5 like that

Answer 1

string s = string.Join(",", valueString.Select(
     (c, i) => (i + (int)(c-'0')) % 10));

or in 2.0:

string[] result = new string[valueString.Length];
for(int i = 0; i < result.Length ; i++) result[i] =
         ((i + (int)(valueString[i] - '0')) % 10).ToString();
string s = string.Join(",", result);