allocating zero bytes

[Serve Laurijssen]

char *s = new(std::nothrow) char[0];

std::cout << (void *)s << std::endl;

On my machine the value of s does not equal NULL. What does the standard say
about that?

 

[peter koch]

 char *s = new(std::nothrow) char[0];

 std::cout << (void *)s << std::endl;

On my machine the value of s does not equal NULL. What does the standard say
about that?

This is fine and defined. Remember to delete [] when you have finished
using the pointer. I assume you are on an embedded platform doing
this? I would normally expect std::vector or std::string to be better
for this (calling terminate if the allocation should fail).

/Peter

 

[Serve Laurijssen]

"peter koch" <[email protected]> schreef in bericht

char *s = new(std::nothrow) char[0];

std::cout << (void *)s << std::endl;

On my machine the value of s does not equal NULL. What does the standard
say
about that?

This is fine and defined. Remember to delete [] when you have finished
using the pointer. I assume you are on an embedded platform doing
this? I would normally expect std::vector or std::string to be better
for this (calling terminate if the allocation should fail).

After allocating zero, is the following UB then?

std::cout << *s << std::endl;

 

[Jack Klein]

"peter koch" <[email protected]> schreef in bericht

char *s = new(std::nothrow) char[0];

std::cout << (void *)s << std::endl;

On my machine the value of s does not equal NULL. What does the standard
say
about that?

This is fine and defined. Remember to delete [] when you have finished
using the pointer. I assume you are on an embedded platform doing
this? I would normally expect std::vector or std::string to be better
for this (calling terminate if the allocation should fail).

After allocating zero, is the following UB then?

std::cout << *s << std::endl;

Please find the setting in your Windows Mail program to properly quote
material in your reply. Thank you.

As to your follow-up question, yes, it is undefined behavior. There
are exactly 0 bytes that you may access through that pointer, which is
exactly what you asked for.

--
Jack Klein
Home: http://JK-Technology.Com
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