String Arrays

Question

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.