Difference between scanf() and strtol() / strtod() in parsing numbers

Question

Note: I completely reworked the question to more properly reflect what I am setting the bounty for. Please excuse any inconsistencies with already-given ans

Answer 1

For the input to the scanf() functions and also for strtol() functions, in Sec. 7.20.1.4 P7 indicates: If the subject sequence is empty or does not have the expected form, no conversion is performed; the value of nptr is stored in the object pointed to by endptr, provided that endptr is not a null pointer. Also you must be considering that the rules of parsing those tokens which are defined under the rules of Sec. 6.4.4 Constants, rule that is pointed in Sec. 7.20.1.4 P5.

The rest of the behavior, such as the errno value, should be implementation specific. For example at my FreeBSD box I got EINVAL and ERANGE values and under Linux the same happens, where the standard referrers only to the ERANGE errno value.