Sept. 2, 2020
10:24 a.m.
Yep, I know that isValidIsbn is the method that must output if a isbn is valid or not. What I want to do is take the first 9 characters out so I can convert them to a array of numbers where I can do the calculation on. And take out the last char so I can seperate test if that is a valid char. So between the 0 and 9 or a X I do not think I would have do all the checks in that only method because it would be a very big method then. but if I understand you well also the test if a string is empty should be called from the isValidIsbn method or even checked there. Roelof