diff options
Diffstat (limited to 'contrib/isn/isn.c')
| -rw-r--r-- | contrib/isn/isn.c | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/contrib/isn/isn.c b/contrib/isn/isn.c index 40942750feb..22bdf62641c 100644 --- a/contrib/isn/isn.c +++ b/contrib/isn/isn.c @@ -443,16 +443,23 @@ ean2ISBN(char *isn) char *aux; unsigned check; - /* the number should come in this format: 978-0-000-00000-0 */ - /* Strip the first part and calculate the new check digit */ - hyphenate(isn, isn + 4, NULL, NULL); - check = weight_checkdig(isn, 10); - aux = strchr(isn, '\0'); - while (!isdigit((unsigned char) *--aux)); - if (check == 10) - *aux = 'X'; - else - *aux = check + '0'; + /* + * The number should come in this format: 978-0-000-00000-0 + * or may be an ISBN-13 number, 979-..., which does not have a short + * representation. Do the short output version if possible. + */ + if (strncmp("978-", isn, 4) == 0) + { + /* Strip the first part and calculate the new check digit */ + hyphenate(isn, isn + 4, NULL, NULL); + check = weight_checkdig(isn, 10); + aux = strchr(isn, '\0'); + while (!isdigit((unsigned char) *--aux)); + if (check == 10) + *aux = 'X'; + else + *aux = check + '0'; + } } static inline void |