atoi() binary unsafe?

ape · **Joined:** 01 Dec 2009 03:25 **Posts:** 1

I recently was told I should use strtol instead of atoi...but I don't really see the rationale behind it.

hcs · **Posted:** 01 Dec 2009 07:19

atoi has no way to indicate an error. As the GNU manpage says:

The behavior is the same as
strtol(nptr, (char **) NULL, 10);
except that atoi() does not detect errors.

aluigi · **Posted:** 01 Dec 2009 14:40

another alternative is using sscanf:
if(sscanf(string, "%d", &number) == 1) printf("ok %d\n", number);

hcs · **Posted:** 02 Dec 2009 13:39

Your sscanf has half the issue of atoi: while it will correctly appear to fail if there are no decimal digits at the beginning of the string (optionally prefixed by whitespace), it will bail out when it hits invalid characters without reporting any errors. For instance:
const char string[] = "123h"

Luigi Auriemma

atoi() binary unsafe?