Doubt on new operator

[edu.mvk]

Do we need to check for error condition when we use new operator in C++
instead of malloc?

Thanks.

[sy8111.public]

edu.mvk wrote:

Do we need to check for error condition when we use new operator in C++
instead of malloc?

By default, operator new will throw std::bad_alloc exception if memory
allocation fails. However, if you don't like exception handling and
want old C-style null pointer check, you can use operator
new(std::nothrow).

In this way, null pointer is returned to indicate memory failure. You
have to include <newto use this feature.

[Kai-Uwe Bux]

edu.mvk wrote:

Do we need to check for error condition when we use new operator in C++
instead of malloc?

Sure! Well, on second thought it may depend on the project requirements.
However, remember that new() will not return 0 but throw bad_alloc if it
fails.
Best

Kai-Uwe Bux

[James Bannon]

edu.mvk wrote:

Do we need to check for error condition when we use new operator in C++
instead of malloc?

Thanks.

See also the other replies. A more general point however is to ask what
we can really do about it if memory is actually exhausted? Not much I
think other than stop gracefully in the new handler. We certainly can't
acquire more if there's none left to acquire, unless we create some kind
of "overflow" mechanism such as virtual memory. Most OS these days
supply such a mechanism, unless we're talking about an embedded control
environment where you would be using a special-purpose allocator anyway.

Cheers
Jim.

[Daniel T.]

In article <rQ*****************@newsfe1-win.ntli.net>,
James Bannon <ja**********@ntlworld.comwrote:

edu.mvk wrote:

Do we need to check for error condition when we use new operator in C++
instead of malloc?

Thanks.

See also the other replies. A more general point however is to ask what
we can really do about it if memory is actually exhausted? Not much I
think other than stop gracefully in the new handler.

Try to be more imaginative. Let's say we are working in a system and at
least two of three different modules have to be in place for the program
to work correctly, the third module is a "nice to have" feature. If
there isn't enough RAM for this third feature, we want the user to still
have the option of continuing without it...

[Julián Albo]

Daniel T. wrote:

Do we need to check for error condition when we use new operator in C++
instead of malloc?

Thanks.

See also the other replies. A more general point however is to ask what
we can really do about it if memory is actually exhausted? Not much I
think other than stop gracefully in the new handler.

Try to be more imaginative. Let's say we are working in a system and at
least two of three different modules have to be in place for the program
to work correctly, the third module is a "nice to have" feature. If
there isn't enough RAM for this third feature, we want the user to still
have the option of continuing without it...

Who is supposed to use new? The module, or the program that wants to use the
feature? In the first case, the program can catch the exception and do
whatever it wants, the module just has to ensure his initialization is
exception safe, no need to catch the exception himself.

--
Salu2

[mlimber]

Daniel T. wrote:

In article <rQ*****************@newsfe1-win.ntli.net>,
James Bannon <ja**********@ntlworld.comwrote:

edu.mvk wrote:

Do we need to check for error condition when we use new operator in C++
instead of malloc?

See also the other replies. A more general point however is to ask what
we can really do about it if memory is actually exhausted? Not much I
think other than stop gracefully in the new handler.

Try to be more imaginative. Let's say we are working in a system and at
least two of three different modules have to be in place for the program
to work correctly, the third module is a "nice to have" feature. If
there isn't enough RAM for this third feature, we want the user to still
have the option of continuing without it...

Or, we might have memory pools (cf.
http://www.parashift.com/c++-faq-lit...tml#faq-11.14), and one
pool is exhausted so we could switch to another.

Cheers! --M