Title: The Wall

Dear Francis

In C Vu 12.2 March 2000 Catriona Siobhán O'Connell contributed more code related to the ISBN competition which was started before I even joined ACCU. In her critique in C Vu 11.6 of some earlier ISBN code by Phil Collings, she correctly pointed out that not "everyone works with ASCII character sets" (point 3, page 27). The eliminate function she presented in C Vu 11.6 isn't compatible with all character sets though.

EBCDIC (pronounced "ebb-see-dick" and short for Extended Binary Coded Decimal Interchange Code, used by some kinds of IBM machine) does not always go well with that eliminate function. Dangerous thing is, it can work for some inputs and exhibit relatively minor inaccuracies for others. The example of removing the vowels in the character string "Catriona Siobhan O'Connell" does not result in the string undergoing the correct transformation but it almost gives the correct answer (in this case). (What does result is the right answer but the capital 'C's and the lowercase 'h' are also gone.) Some slight variations can dangerously yield misleadingly correct results (such as if the capital letter 'C' is changed everywhere to capital 'W'; with lowercase 'h' changed to lowercase 'q'; along with capital 'O' turning into a capital 'E').