Re: 80286 protected mode

On 09/10/2024 20:10, Thomas Koenig wrote:

David Brown <david.brown@hesbynett.no> schrieb:
 

When would you ever /need/ to compare pointers to different objects?
For almost all C programmers, the answer is "never".

 Sometimes, it is handy to encode certain conditions in pointers,
rather than having only a valid pointer or NULL.  A compiler,
for example, might want to store the fact that an error occurred
while parsing a subexpression as a special pointer constant.
 Compilers often have the unfair advantage, though, that they can
rely on what application programmers cannot, their implementation
details.  (Some do not, such as f2c).

Standard library authors have the same superpowers, so that they can implement an efficient memmove() even though a pure standard C programmer cannot (other than by simply calling the standard library memmove() function!).