How to calculate the sum of 2 numbers with BrainFuck

Question

I\'m trying to write a program with BrainFuck that can read two numbers up to 9, calculate the sum of them and then print the result out, e.g. 3 & 5 give the result 8 .

Answer 1

I built a code that will work with an infinite amount of input numbers but it can only output 1 or 2 digits so the range of the sum of digits can be 0-99

>,                     go to cell #1 and read input
[                      loop while input is not null
  >+++++++[<------->-] subtract 49 from input
  <+                   add 1 to input so we have the value of the input numeral in cell #1
  [-<+>]               add cell #1 to cell #0
  ,                    read next numeral
]                      repeat until no number is being input (the input number can be longer than two digits)
>-                     go to cell #2 and set it to minus 1 so the loop will run (i will explain that at the end of the loop)
[                      loop while number in cell #0 is greater than 9
  +                    set the value of #2 to 0
  <[->+>+<<]           copy the value of #1 to #2 and #3
  >>[-<<+>>]           copy the value of #3 back to #1
  <<<                  go to #0
  [->>>+>+<<<<]        copy it to #3 and #4
  >>>>[-<<<<+>>>>]     restore it in #0
  <                    go to 3
  [-[-[-[-[-[-[-[-[-[  check if number is greater than 9
  <<+<----- ----->>>   if yes increment number in cell #1 and decrease number in cell #0 by 10
  [-]]]]]]]]]]]        set #3 to 0 so we can leave the loop
  <<                   go to #1
                       we need to check if the number in cell #1 was incremented
                       cell #2 will store the most recent value of cell #1
  [->->+<<]            so we subtract the value of cell #2 by the value of cell #1 and 
                       store the value of cell #1 in cell #3
  >>[-<<+>>]           restore the value of #1
  <                    go back to cell #2
]                      if cell #1 was increased then cell #2 will be minus 1 and the loop will restart
<[>+++++++[<+++++++>-] if cell #1 is greater than 0 then add 49 to it
<-.[-]]                subtract 1 so we have the ascii code of the value in #1 then print it and set it to zero
+++++++[<+++++++>-]<-. do the same with the value in cell #0

or in short:

>,[>+++++++[<------->-]<+[-<+>],]>-[+<[->+>+<<]>>[-<<+>>]<<<[->>>+>+<<<<]>>>>[-<<<<+>>>>]<[-[-[-[-[-[-[-[-[-[<<+<---------->>>[-]]]]]]]]]]]<<[->->+<<]>>[-<<+>>]<]<[>+++++++[<+++++++>-]<-.[-]]+++++++[<+++++++>-]<-.