How to calculate many sums in a single foreach relating the same data?

That is a great improvement. I will update my local version. Thanks :-)

Thanks Stefan, it works great! To use the rule in a validation of a text field I only added refreshvariables in the IsIbanValidHelper, to avoid an error. Thanks a lot.

Thank you Stefan Helzle, this will help me a lot!!!!

The implemented algorithm is

https://en.wikipedia.org/wiki/International_Bank_Account_Number#Modulo_operation_on_IBAN

The trick here is, to use the initial parameter of the reduce function like a shared memory dictionary which is modified on each iteration.

Have fun :-)

IsIbanValidHelper: dict(any)
if(
  isnull(ri!dict.bban),
  ri!dict,
  a!localVariables(
    local!checksum: mod(tostring(ri!dict.checksum) & left(ri!dict.bban, ri!dict.num), 97),
    local!bban: right(ri!dict.bban, len(ri!dict.bban) - tointeger(ri!dict.num)),
    {
      checksum: local!checksum,
      num:7,
      bban: local!bban
    }
  )
)

IsIbanValid: iban(text)
a!localVariables(
  local!iban: upper(stripwith(ri!iban, " ")),
  local!checksum: left(local!iban, 4),
  local!ban: right(local!iban, len(local!iban) - 4),
  local!bban: local!ban & local!checksum,
  local!replaceChars: {touniformstring(enumerate(10)), "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"},
  local!replaceNums: {enumerate(10), enumerate(26)+10},
  local!newbban: joinarray(
    a!forEach(
      items: enumerate(len(local!bban)),
      expression: displayvalue(
        local!bban[fv!index],
        local!replaceChars,
        local!replaceNums,
        ""
      )
    )
  ),
  local!result: reduce(
    rule!IsIbanValidHelper(
      dict:_,
      dummy:_
    ),
    {
      checksum: 0,
      num: 9,
      bban: local!newbban
    },
    enumerate(ceiling(len(local!newbban) / 7))
  ),
  tointeger(local!result.checksum) = 1
)

Hi Stefan, me too I need this solution for a IBAN validation!!!... Thanks

Sure. Please connect me here in Appian community and let's have a direct chat.

Hi Stefan, 

do you still have the code for checksum algorithm for IBAN Validation in Appian?

You would be of great help to me.

Thanks!

Thanks Stefan, I keep this function on hand :-)

Thank you Mike, sugasanr.
It's great ! I did not know we could do that with a dictionnary.

There is an option using reduce() which allows you to pass data from one iteration to the next. I used it to implement a block based checksum algorithm for IBAN validation. But in this case I would prefer this simple one.