As a perfect example of how horrible strtol() is, let's look at his example code:
int i1 = strtol(s, &endptr, 0); if (*endptr != ',') goto bad;
int i2 = strtol(endptr+1, &endptr, 0); if (*endptr != ',') goto bad;
int i3 = strtol(endptr+1, &endptr, 0); if (*endptr != '\0') goto bad;
bad: /* error case */
Can you spot the bug? What about an input like ",2,3" ? Nicholas does mention that this code is broken for underflow or overflow (you must wrap every singe call like this: "errno = 0; strtol(...); if (errno...)") but either missed this or considered it irrelevant. It's just too hard to get right.
Just use the *scanf() family (yes, that's hard to use too). Be suspicious of any code using either strtol() or atol().