| Topic: |
DEVELOP > c-Plus-Plus |
| User: |
"Serve Laurijssen" |
| Date: |
20 Jan 2008 11:42:09 AM |
| Object: |
allocating zero bytes |
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?
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| User: "peter koch" |
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| Title: Re: allocating zero bytes |
20 Jan 2008 11:53:21 AM |
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On 20 Jan., 18:42, "Serve Laurijssen" <n...@hao.com> wrote:
=A0char *s =3D new(std::nothrow) char[0];
=A0std::cout << (void *)s << std::endl;
On my machine the value of s does not equal NULL. What does the standard s=
ay
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
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| User: "Serve Laurijssen" |
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| Title: Re: allocating zero bytes |
20 Jan 2008 12:28:49 PM |
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"peter koch" <peter.koch.larsen@gmail.com> schreef in bericht
news:d17eaa53-2e0b-4bcb-a754-0dcd98404013@j20g2000hsi.googlegroups.com...
On 20 Jan., 18:42, "Serve Laurijssen" <n...@hao.com> wrote:
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;
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| User: "Jack Klein" |
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| Title: Re: allocating zero bytes |
20 Jan 2008 01:17:33 PM |
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On Sun, 20 Jan 2008 19:28:49 +0100, "Serve Laurijssen" <ni@hao.com>
wrote in comp.lang.c++:
"peter koch" <peter.koch.larsen@gmail.com> schreef in bericht
news:d17eaa53-2e0b-4bcb-a754-0dcd98404013@j20g2000hsi.googlegroups.com...
On 20 Jan., 18:42, "Serve Laurijssen" <n...@hao.com> wrote:
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
FAQs for
comp.lang.c http://c-faq.com/
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alt.comp.lang.learn.c-c++
http://www.club.cc.cmu.edu/~ajo/docs/FAQ-acllc.html
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