well the 1st question is, why not just use skill11 to skill14?
2ndly str_for_num generates strings with 3 decimals, so your string length (str_len if you wanna check this) is 10
3rdly, most str functions are slow or medium speed, so you don't really want to be doing this every frame, by the looks of what you have there i'd have
while (my_selected_target != Selected_target)
to only recalculate this once my_selected_target has changed
finally, instead of doing all that, you could use skill11 to store a stuct, and save all the data in there that you need
hope this helps
