[Info-vax] Significance of 2020 / 2021 date

[John Dallman]

In article <i5tpv6Fnj2hU1 at mid.individual.net>, bill.gunshannon at gmail.com
(Bill Gunshannon) wrote:
> On 1/9/21 8:27 AM, Bill Gunshannon wrote:
> > On 1/9/21 7:35 AM, Andy Burns wrote:

>>>>> if (atoi (date_string + 5)>  2020)

> >> atoi requires a *pointer* to an asciiz string, presumably in 
> >> this case the format is something like DDMMMYYYY, so that the +5 
> >> starts the decimal conversion from the address of the first Y.
> > I would have expected the original to generate an error at compile
> > time.

> OK, it made me curious enough that I tried a few examples.  
> Apparently the compiler (at least gcc) doesn't really care what you
> throw at the call to atoi().

It takes a char* pointer, and assumes the string is terminated by a zero
byte. The +5 is just moving the pointer along by 5 characters, producing
a new pointer. 

This is perfectly legal C code. Not good modern style, but entirely legal.


John