Re: May a string span multiple, independent objects?

On 7/3/24 11:23, Hans-Bernhard Bröker wrote:

Am 03.07.2024 um 16:31 schrieb Vincent Lefevre:

ISO C17 (and C23 draft) 7.1.1 defines a string as follows: "A string
is a contiguous sequence of characters terminated by and including
the first null character."
>
But may a string span multiple, independent objects that happens
to be contiguous in memory?
>
For instance, is the following program valid and what does the ISO C
standard say about that?

 
Comparing pointers pointing at distinct objects is already invalid (for
some interpretation of "invalid")

Comparison of valid pointers that point at distinct objects has
well-defined behavior. Such operations would be pretty useless if that
weren't the case, since they only compare the locations of those objects
- if they were allowed only for objects that are  not distinct, the
locations would necessarily be the same, so, ==, <= and >= would always
return true, and !=, <, and > would always return false.

Furthermore, comparison for equality (as opposed to comparison for
relative order) is permitted even for objects that aren't sub-objects of
the same larger object. The problems with such code involves
incrementing and dereferencing such pointers, not comparing them.