Simple, but do you know how to read in a single character? If you do then just put the incoming characters in an array, not a string, (you can but strings are highly NOT recommended). After each prompt, get the data, store it in an array then change the array. You can use a 2D array as such, "My_Array[10][3]"
My_Array[data_count][switch_count] = var;
Everytime you enter a new char, you update the data_count and store the new character. Then once you get everything from the first prompt, update switch_count, and repeat. Second prompt, repeat.
Or same idea but with seperate arrays, Array1[], Array2[], Array3[].
I have a Windows forms application, written in C# that you could add text fields and labels to. Remove the existing text entry field, and change the send button to get data from all three fields to send. If you are interested, PM me with an e-mail address and I'll send it to you.