hi I am in a process of designing relational calculator. If a user supplied a string like -3.33+44*456/2.2-3+4.... I want to store it in string array as -3.33 +44 * 456 / 2.2 -3 +4 ...... (that is *, /, +ve value, -ve value separately and in serial order into an string array) This is the code I wrote: string a = "-3.33+44*456/2.2-3" string[] ip = new string[25]; int k = 0; for (int i = 0; i < a.Length; i++) { if (a.Substring(i, 1) == "+" || a.Substring(i, 1) == "-" || a.Substring(i, 1) == "*" || a.Substring(i, 1) == "/" || a.Substring(i, 1) == "^") { for (int j = i + 1; j < a.Length; j++) { if (a.Substring(j, 1) == "+" || a.Substring(j, 1) == "-" || a.Substring(j, 1) == "*" || a.Substring(j, 1) == "/" || a.Substring(j, 1) == "^") { if (a.Substring(i, 1) == "+" || a.Substring(i, 1) == "-") { ip[k] = a.Substring(i, j-i); k++; } else { ip[k] = a.Substring(i, 1); k++; ip[k] = a.Substring(i + 1, (j -i)-1); k++; } i = j; break; } } } } But its not working properly: Its storing only one element in the array. From last two days I am braking my head. Please help me. Thank You.